OHS Worker Fatalities Report

7/25/2019 OHS Worker Fatalities Report

1/43

Workers Crushed y

Collapse

of Tank Roof Support Structure

Date of Incident: pril 24 2007

Type of Incident: Double Fatality

2 Serious Injuries

3

Minor

Injuries


2/43

TABLE

OF CONTENTS PAGE NUMBER

SECTION

1.0

DATE

AND TIME

OF

INCIDENT

3

SECTION

2.0

NAME

ADDRESS

OF PRINCIPAL

3

ST

AKEHOLDER S)

-

Owner s)

-

Prime

Contractor

-

Employer s)

-

Stakeholders

SECTION

3.0

DESCRIPTION OF PRINCIPAL

4

STAKEHOLDER S)

SECTION

4.0

LOCATION

OF

INCIDENT

6

SECTION 5.0

EQUIPMENT

AND

MATERIAL INVOLVED

7

SECTIO N 6.0 NA

RRATIVE DESCRIPTION

OF

INCIDENT

8

SECTION 7.0

ANALYSIS 12

SECTION

8.0

APPLICABLE LEGISLATION

14

SECTION

9.0 FOLLOW-

UP/ACTION

TAKEN

17

SECTION

10.0

SIGNATURES

18

SECTION

11.0

ATTACHMENTS

18

2

September

7

,

20

07


3/43

File: F-536919

Section 1.0 DATE AND TIME OF INCIDENT

1.1 April 24, 2007, approximately 2:30 p.m.

Section 2.0 NAME ADDRESS OF PRINCIPAL STAKEHOLDER S)

2 1 Owner s)

2.

1

I Canadian Natural Resources Limited

2500-855 2 Street SW, Calgary, Alberta T2P 41 8

2.2 Prime Contractor

2.2.

Ca

nadian Natural

Re

sources Limited Horizon Oil Sands Corporation (CN

RL

Horizon)

PO Bag

4025, Fort

McMurray

, Al

berta

T9H 3H5

2.3 Employer 1

2.3. 1 SSEC Canada Ltd. SSEC Canada)

1800, 250-6 A venue,

Ca

lgary, Alberta T2P

3H7

2.4 Employer 2

2.4. Tenth Construction Company of Sinopec (TCC)

PO Box 132, Zibo, Shandong, China 255438

2.5 Stakeholder 1

2.5. 1 Sinopec Shanghai Engineering Company Ltd. SSEC China)

769 Zhangyang Road, Pudong New Area, Shanghai, China

2.6 Stakeholder 2

2.6.1 China Petrol

eum

and Chemical [Petrochemical] Corporation (Sinopec)

PO Box 3013, Beijing 100011, China

2.7

Stakeholder 3

2.7.1 The Zachry Group

Suite 250, 700 Sixth Avenue SW, Calgary, Alberta, T2P OT8

3

September 27, 2007


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File: F-536919

2.8 Stakeholder 4

2.8.1 Zachry Energy International Inc

1238, 13351 Commerce Parkway, Richmond, British Columbia V6V 2X7

2.9

Stakeholder 5

2.9.1 TIW Division

of

Canadian Erectors Ltd. (TIW)

23 Smith Street, St. Catherine's, Ontario L2R 6Y6

Section 3.0 DESCRIPTION

O

PRINCIPAL STAKEHOLDER S)

3.1 Canadian Natural Resources Limited CNRL)

3 1.1

CNRL

is a senior independent oil and natural gas exploration, development and

production company based in Calgary, Alberta.

3.1.2 The CNRL Horizon Oil Sands Project is located approximately 7 m north ofFort

McMurray and 3 km north of Fort MacKay, Alberta. CNRL owns and operates

leases covering approximately 115,000 acres and will use open pi t mining

me

thods to

mine oil sands. A plant is being constructed that will separate raw bitumen from the

oil sands and upgrade the bitumen to a synthetic crnde oil using delayed coking and

hydro-treating technologies. Phase 1 started in 2005 and is scheduled fo r completion

in 2008, ramping up to produce 11 0,000 barrels of synthetic crude oil per da

y

Phases

2 and 3

wi ll

proceed until projected completion in 20 12 Phase 3 is expected to bring

production to 232,000 barrels of synthetic crude oil per day. At the time of the

incident approximately 6,000 workers were working on the construction of the

project.

3.2 SSEC Canada Ltd. SSEC Canada)

3.2.1 SSEC Canada is an Alberta corporation. The company was incorporated in April,

2006 to bid for work in the Alberta oil sands.

The

company is 90 owned

by

SSEC

China, a Chinese company, and 10 owned

by

Zachry Energy International Inc., a

companybased in British Columbia. SSEC Canada uses management, technical and

journeyman workers drawn from

SSEC China and Tenth Construction Company

of

Sinopec (TCC), working in Alberta as temporary foreign workers, to carry out

projects such as the tank farm project at the

CNRL

Horizon Oil Sands Project.

3.2.2 SSEC Canada was contracted by CNRL Ho

ri

zon to construct a total of 14 tanks, 11

on the east tank farm and 3 on the west tank farm at the CNRL Horizon Plant Site.

The effective date of he contract was April 11 , 2006. SSECCanada was expected to

have workers available July 2006 to commence the tank assembly at the west tank

farm. Wo rk on the three tanks at the west tank fan11 was scheduled for completion by

September, 2007.

September 27, 2007


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Fil

e:

F-536919

3.2.3 The three tanks on the west tank farm were being constructed in accordance with a

tank erection schedule prepared by CNRL. The schedule specified a

se

quence of

construction where the tank floors were laid, the walls were started and the internal

roof support structures were erected. SSEC Canada was required to construct the

tanks in accordance with

th

e tank erection sched

ul e

and in accordance wi

tb

component and mate

ri al sc

hedules and engineered drawings provided by

TIW

. The

TIW drawings showed how the components and materials they had supplied fitted

together. SSEC Canada was responsible for the direction of their workers, which

included giving

in

structions on how component

pa

rts of the roof suppo

rt

structure

were to be suppotied from movement or falling until the construction was complete

and the tank assemblies were self-supporting.

3

.3

Tenth Construction Co

mpan

y

of

Sinopec (TCC)

3.3. l TCC is an industrial construction company in China, specializing in the construction

and in stallat ion of petroleum refining projects. TCC has undertaken construction

projects in Africa, Asia and Saudi Arabia.

3 4 Sinopec

Shanghai Engineering Company

(SSEC

China

SSEC

China is a Chinese company based in Shanghai, Ch ina. SSEC China has the

capacity to undertake mid

to large engineering projects including projects in the

petrochemical industry. SSEC China has some contacts with engineering companies

inte

rn

ationally. SSEC China own a 90% share of SSEC Canada and exercises full

control of all activities of SSEC Canada.

The

Horizon tank project was sub

contracted to

TCC

by

SSEC China. All workers were recruited by

TCC

. Most

construction management personnel were employed by TCC. SSEC China employed

one

bus

in

ess representa

ti

ve

in Ca

lgary to deal with the finances and one secretary at

the CNRL sit

e.

3.5

Sinopec C

hina Petroleum

and Chemical Petrochemical Corporation (Sinopec)

3.5 .1 Sinopec is the largest producer and marketer of refined oil products in China and

Asia, and is the largestproducer and distributor of petrochemicals in China. Sinopec

is a state-owned Chinese corporation, is the second largest oil and gas explorer in

China, and is the parent co

mpany

of

both TCC and SSEC Chin

a.

3.6

T

he Zachry Group

3.6 .1 The Zachry Group is an Alberta registered company that designs and manufactures

equipment fo

r the oil and gas, pulp a

nd

paper, sawm

ill

s and mining industries.

5

September 27, 2007


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File: F-536919

3.

7.

Zachry Energy International Inc.

3.7.1 Zachry Energy International Inc. is a British Columbia registered company that is

60% owned by the Zachry Group. Zachry Energy International Inc. provides

overview and management input to SSEC Canada and is 10% shareholder

ofSSEC

Ca

nada. Zachry International Inc. focused on helping

SSEC

Chin a to liai

se

with

CNRL and to penetrate the oil and gas construction market in Alberta. They were

responsible to assist SSEC China to

li

aise with

CNRL

and assist with requirements

of

training

of

he trade workers.They were responsible to assist SSEC China workers to

obtain work visas, and coordinated with Alberta Apprenticeship and Indust ry

Training (AAIT) requirements for designated trades.They assisted SSEC China to set

up SSEC Canada Ltd. , and assisted SSEC Canada Ltd. with obtaining legal counsel

to help the company deal with local regulations and laws in connection with their

establishment in Alberta. In March of

2007 Zachary Energy International Inc.

relinquished its 10% share

of

SSEC Canada. SSECChina and Sinopec requested that

Zachary Energy International Inc. be the lead contact for SSEC Canada in relation to

the investigation ofWHSC with respect to the April 24, 2007 incident at the

CNRL

Horizon site.

3.8 T W Division of Canada Erectors Ltd. TIW)

3.8. l TIW is engaged in the fabrication, construction and distribution sectors

of

the stee l

industry.

TlW

is a fully integrated unit for design, manufacturing and construction of

fi eld erected steel platework structures.TIW was contracted byCNRL to provide the

components, material schedules for arriva l on site, and the engineered drawings for

th e 14 tanks on the east and west tank fanns at the CNRL Horizon plant site.

3 .8.2 The

roof

support structures were all fabricated in house by TIW at their faci i ies,

with the exception

of

the weldingofcolumns to the cap plates, which was perfo1med

by Bartonair Fabrications of Hamilton. Bartonair is a regular supplier to TIW.

Bartonair was required to use TIW supplied materials, consumables and welding

procedures. TIW inspection personnel reviewed the materials before shipment. TIW

coordinated the identification, packaging and shipment

of

he

roof

support structures

(including columns) to the CNRL Horizon site.

Section 4.0 LOCATION OF INCIDENT

4.1 Tank 72-TK- l B, located on the west tank farm of the CNRL Horizon Oil Sands

Project,

approximately

70

km north

of

Fort McMurray and 30 km north

of

Fort

MacKay, Alberta.

6

September 27, 2007


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Fi

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Section 5.0 EQUIPMENT AND MATERIAL INVOLVED

5.1

he

West Tank Farm

5 .1 I The west tank farm is located approximatel y northwest of centre on the Horizon Plant

Site. (Attachment

C ,

Site Layout

).

As

the tanks had restricted

mea

ns

of

entry and

exit and could become hazardous to workers entering them, they were designated as

confined space. Three high-cone steel tanks, Tank 72-TK-lA, 72-TK- IB and 72-TK-

1

C

are located on

the

west tank farm, in a line east to

west

with Tank 72-TK-1A at

the

west, Tank 72-TK-

lB in

the centre and Tank 72-TK- lC at the east end of he row

of tanks.

The

tanks are

all

the same size and of the sa

me

construction. At the time of

the incident the

roof

support structure in tank 72-

TK

-

l

B was in a suspended state of

completion with the centre support column, the inside ring of6 support columns and

the outer ring of 12 support columns in place, with the girders and rafters fitted,

waiting for the she ll assembly to be completed. Once the she ll assembl y was

completed,

th

e rafters from the outer ring 's girders would be connected to the she

ll

wal1. The roof support structure in

ta

nk 72-TK-1 B had been completed the day before

the co llapse. At the time of

th

e incident a team

of

bo ilermakers and scaffolders was

working in Tank 72 -TK-1 C on the assembly of th e roof support structure.

(Attachment A'', Photographs 1 1, #15)

5.2

The East

ank

Farm

5.2.1 The east tank farm is located at the east

of

the Horiz

on

Plant Site (Attachment

C'

',

Site Layout).

When

completed, the east tank farm will contain 10 tanks of various

siz

es

, and

of

generally similar construction to the tanks

on the

west tank fann. At the

time

of the

incident,

the

roof support structures in two tanks

on the

east tank farm,

Tank 73-TK-11

and

73-TK-12 were also in a suspended state

of

assembly waiting for

the shell walls to be competed. After which they would connect the rafters from the

outer rin

gs'

girders to the top of th e she

ll

wa

ll

s.

(A

ttachm ent A , Phot

ogra

ph #17)

5.3

Tank 72 TK tB

5.3. 1

Ta

nk 72-

TK-l

B (described as a Dilbit Dewatering

Ta

nk), located on the west tank

farm, was to be a circular steel high-cone roof tank, 56.5 mi n diameter and 19.8 m

hig

h.

At the time

of

the incident the tank wa

ll

she

ll

was only completed to a height of

5.6 m.The tank structure consists of wall,

fl

oor and roof constructed from steel plate.

The

roof

is constructed onto a

roof

supp

or

t

st

ructure cons isting

of

vertical circular

column

s,

supporting girders and

ra

dial rafters. (Attachment D , Sketch of Roof

Support Structure). The components of th e roof support structure are assembled

together

with

19 mm

X

inch) nuts and bolts. At the time of the incident a team of

welders was working in the tank constructing the tank wall. Two technicians were

also in the tank carrying out weld testing, and one scaffolder

wa

s in Tank 72-TK-l

B.

There was an Electrical Consultant and awelding foreman who we re checking out a

we lding machine on top

of

the wa ll .

7

September 27, 2007


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File: F-536919

5.4

ssembly Procedure for

Tanks

5.4.1 SSEC Canada developed a procedure

fo

r assembling and supporting the tank roof

support structures for the tanks on the west tank farm. Erection of the shell was

independent

of

the

roof

support structure - they were being assembled concurrently.

The procedure consisted ofraising the centre support column first, using a crane and

securing it in the ve1

ica

l position by workers operating elevating work platfo

1m

s to

in

stall 4 steel cables, secured to the top of the column and anchored to lugs welded

onto the tank floor

The

cables were tightened using

co

me-alongs . ( Come-along

is a generic tenn to de

sc

ribe mechanical tensioning devices). The inner ring of 6

support columns was erected in a similar manner, but with 3 cables on each column.

The girders connecting the inner ring of columns were then lifted and bolted into

place, using 19 mm ( :y ; inch) bolts, and the ra

di

al rafters were installed between the

centre column and the inner ring. After the inner ring was completed, one cable,

extending towards the ta

nk

centre, was removed from each

of

the 6 inner ring

columns The outer ring of 12 columns was erected, using 3 cables to support each

column. The girders connecting the outer ring ofcolumns were lifted and bolted into

place, and all of the radial rafters were installed. After

th

e outer ring of the

roof

support structure was assembled, 6 steel cables were installed, extending from girders

to alternate columns in the outer ring to anchor lugs welded into the floor of he tank,

close to the tank wall. When

th

ese 6 support cables were in place and tightened using

come-alongs'', all of the cables used to support the individual columns were

removed. The six cables remaining were intended to support and stabilize the

roof

sup port structure unt il the she ll was completed to ful l height The come-alongs

were removed after the cables had been tightened.

Section 6.0 N RR TIVE DESCRIPTION OF INC IDENT

6. 1 SSEC Canada recruited 132 Mandarin-speaking Chinese workers from TCC to work

as temporary foreign workers on the CNRL tank construction project.

The

workers

had at least 5 years expe

ri

ence as trades-people and had recei ved additional training

from a Canadian training agency before arriving in Canada.

The

workers started to

arrive

in

Canada

in

September of 2006.

6.2 On April 24, 2007, at the west tank farm, the

roof

support structures in tanks 72-TK

lA (Attachment

A ,

Photograph #11) and

72-TK-lB

were in the suspended state of

completion waiting for the shell to

be

assembled. Each

roof

sup

port structure was

supported by six cables

The

roof

support structure in tank 72-T

K-lC

was being

assembled The centre column and the inner ring had been completed and the steel

cables were still attached to the columns. No work was taking place

in Tank 72-

TK

l A on April 24, 2007. A team of boilermakers was working in Tank 72-TK-I C,

assembling the roof suppo1t structure. (Attachment A , Photograph #15)

8

September 27, 2007


9/43

6.3

6.4

6.5

Fil

e:

F-536919

On April 24, 2007, a team of welders was working in tank 72-TK-1 B, welding

sections into the tank wall. The tank wall sec

ti

ons were being welded together by

welders and helpers wo rking inside welding machines that tracked around the inside

of the tank wa ll. (Attachment A ,Photographs #20, #21) One Electrical Consultant

and a welder foreman were inside the tank checking an elect

ri

cal failure on one

of

he

we

lding machines. One scaffolder was also on th e

fl

oor area inside the tank. Two

weld test technicians were also in Tank 72-TK-1 B, testing and marking the welds on

the tank wall.

At approximately2:30 p.m. on April 24, 2007, workers inand around tank 72-TK- lB

heard several sounds, described as loud bangs or pops. The roofsupport structure in

tank 72-TK-1 B started to fal l in an easterly direction during windy conditions. As the

structure collapsed, some of the support cables failed, many of th e bolts that were

holding the components together failed and then the components began to come

apart. (Attachment A, Photograph s #8, #9, #10, # 22) The stru cture fell onto the

east side of the tank wall. Some of he components of the roofsupport structure can1e

to rest on th e floor of the tank , some components came to rest leaning against the

tank wall, and some components came to rest on the outside of the tank on the east

side. Many of the components we re bent or damaged by the impact.

Af

ter the roof

support structure co llapsed so

me

of the workers who

were

in tank 72-TK-1 B,

managed to escape from the tank through manways or other holes in the tank wal

(Attachment A , Photographs #1, #2, #3, #4)

SSEC Canada workers from tank 72-T

K-.1

C and other workers on the west tank farm,

as

well

as workers from other contractors who were working near the west tank fa1m ,

went to tank 72-TK-lB to provide assistance. CNRL Horizon emergency services

were called and attended. Rescuers had to lift a large section

of

steel inside the tank

to remove the fatally injured Scaffolder. The Electrical Consultant was standing on

the top of a welding machine, which was located on top of he wall, and was fatally

injured

when he

was struck

by

falling steel. His body was thrown onto scaffolding

outside the tank. The Electrical Consultant was pronounced dead at the scene. The

Scaffolder, who was on the tank floor, was crushed by the falling steel and died in an

eme

rgency conveyance vehicle on the way to Fort McMurray. Two other workers

received serious injuries and three more workers received minor inj uries. The two

se

riously injured workers and two of the workers who had received minor injuries

were transported to hospital in Fort McMurray. The two seriously injured workers

were subsequently transferred to hospital in Edmonto

n.

6.6

INV STIGT ION OBSERV TIONS ND FORMT ION

6.6. 1 Workplace Health and Safety Compliance (WHSC) was notified of the incident by

CNRL Horizon at 3:08 p.m. on April 24, 2007. Workplace Health and Safety officers

from Fo1t McMurray were dispatched to the scene and while en route made contact

with RCMP Fort McMurray Detachment. WHSC officers arrived at the site at

5:

19

p.m

. The scene had been secured

by

CNRL and RCMP.

9

September 27, 2007


10/43

File: F-536919

6.6.2

WHSC

issued a verbal Stop Work Order to CNRL at 8:36 p.m.

on

April 24, 2007.

The Stop Work Order was for construction of the three tanks on the west tank farm

and any similar tanks on the Horizon site.

6.6.3 On April 24, 2007 a WHSC Lead

In

ves

ti

gator was di spatched from Edmonton to

direct the investigation The Lead Investi

ga

tor atTived at the CNRL Horizon Oil

Sands Project at 9:00 am . on April 25, 2007.

CN

RL Ho

ri

zon set up an internal

investigation team a

nd

met with

th

e Lead Investigator a

nd

other Workplace Health

and Safety of

fi

cers on April 25, 2007. The Lead Investigator confirmed the ve

rb

al

Stop Work Order a

nd

reminded CNRL Ho

ri

zon that no workers were

to

enter the

area and to have the area secured.

6.6.4 On April 25, 2007 a seco

nd

WHSC Lead

In

vestigator, the WH SC Manager

of

Compliance, and an employee from another Govenunent of Albe1ta depa1tment, who

speaks Mandarin, were dispatched from Edmonton to assist with the investigation.

The second Lead Investigator, the Manager and the other employee arrived at the

CNRL Horizon plant site at 6:00 p.m.

6.6.5 t was found that there had been

13

workers inside tank 72-TK-lB at the time the

incident occurred.

Ten

workers were Chinese temporary foreign workers employed

by

SSEC Canada, one Chinese worker (the Electrical Consultant) was directly

employed

by

TCC and two workers were Canadian workers employed by Iris

NDT

,

carrying out weld testing. All of the fatally injured and other injured workers were

Chinese temporary foreign work ers. SSEC Canada workers and others who had

attended the scene were interviewed over a pe

ri

od of several days, in o

rd

er to

determine the circumstances of the inc

id

ent and the loca

ti

ons

of

a

ll of

t

he

workers

who were inside the tank at the time of the incident. t was found

th

at

th

e workers

had carri ed out the assembly of

th

e

ro

of suppo

rt

structures in accordance with SSEC

Canada

's

chief engineer

's in

structions a

nd

the assembly drawings prov

id

ed by T IW .

6.6.6 One

of

the

fa

tally injured workers, an Electrical Consultant, had been on the top

of

a

welding m

ac

hine working on

th

e east side of the tank wall. The Electrical Consultant

had been struck in the head and back by a section of the falling steel and thrown onto

scaffolding outside the east wall

of

the tank.

The

other fatally injured worker, a

Scaffolder, had been standing on the tank floor, east of the tank centre, and had been

caught and crushed under a falling girder. Rescuers had manually lifted the girder to

rescue him. The Scaffolder died during transport to hospital. (Attachment

A

,

Photographs #4, #5, #7)

1

September 27, 2007


11/43

6.6.7

6.6.8

6.6 .9

6.6.10

6.6.11

File: F-536919

One

of

the seriously injured workers, Welder l , had been inside the same welding

machine that the Electrical Consultant was working on. The welding machine } ad

been struck by fall ing steel and partially dislodged from the tank

wa

ll. Welder

1

was

trapped inside the welding machine and was rescued by CNRL staff a

nd

other

contract workers.

The

other seriously injured worker, Welder 2, was inside another

welding machine on the east wall that had been struck by falling steel and completely

dislodged from the wall, falling to the tank floor. Welder 2 was rescued by his

Chinese co-workers. (Attachment A , Photographs #5, #6)

The verbal Stop Work Order was confirmed in writing on April 27, 2007. The Stop

Work Order prevented access to the east and west tank farms.

The

Stop Work Order

was re-issued on May 1, 2007 to define a specific part of the east tank farm around

tanks 73-TK-1 and 73-TK 12 where workers could be at risk from the collapse of

the

roof

support structures. The remainder of the east tank farm was released to

CNRL. The Stop Work Order for the west tank farm remained in effect. CNRL

cooperated with the Stop Work Orders and provided barriers and security

staff

to

ensure that the order was made effec

ti

ve.

On May 1

2,

2007 the roof suppo1t structure in tank 72-TK-lA on the west ta

nk

farm

collapsed during windy conditions. The Stop Work Order was st ill in effect and no

workers were near the collapse. Before the collapse it had been observed that the roof

support structure was twisting during windy conditions. (Attachment

A

,

Photographs #18, #19)

CNRL developed an engineered procedure for securing and dismantling the roof

support structures in tanks 73-TK-1 and 73-TK-12 on the east tank farm. The Stop

Work Order for the east tank farm was lifted on May 16, 2007 and the site was

released to CNRL Horizon to enable the remediation work to be done. The work on

dismantling and removal of the roof support structures was completed on June

11

,

2007 by SRS Industrial Services Ltd.

CNRL developed an engineered procedure for the removal of fallen materials in

tanks 72-TK-lA and 72-TK lB and the dismantling of the roof support structure

from tank 72-TK-l C. The Stop Work Order for the west tank farm was lifted on June

6, 2007. Work on tank 72-TK-I A commenced on June

8,

2007

an

d was completed on

June 13, 2007. Work then sta1ted on tank 72-TK-I B a

nd

was completed on June 20,

2007.

The

removal

of

he roofsupport structure in tank 72-TK-l C was completed on

June 22, 2007 by Penny Industrial Fabricators Ltd. The WHSC Lead

In

vestigator

monitored the removal

of

the fallen materials from tanks 72-TK-1A and 72-

TK-1

B

and during the removal retrieved materials from both tanks for analysis by an

independent

co

nsulting engineering firm.

September 27, 2007


12/43

File: F-536919

Section 7.0 ANALYSIS

7 1 Direct ause

7 1.1 Two workers working on the construction ofa large steel tank 72-TK-1 B were fatally

injured two other workers were seriously injured and three workers received min

or

injuries when the

roof

support structure inside the tank collapsed suddenly and

without warning onto the workers.

7 2 ontributing

Factors

7 2. 1 SSEC Canada assembl

ed

the

roof

support structure as a stand alone structure which

was not intended to be assembled as such by the T l drawings. Neither CNRL n

or

SSEC Canada consult

ed

with

TIW

with respect to what assembly sequence should

be

fo ll

owed for the con

st

ruction of the

roof

support structure. As the erection

of

the

shell was independent of the roof support structure and they were being assembled

concun-ently the top of the shell and the outer ring were not supporting each other.

7.2.2 TIW did not specify

an

erection sequence to follow to erect the tank they designed.

TIW did not specify the assembly sequence because that was not part of he contract

with CNRL.

7 2.3 CNRL prepared a tank erection schedule specifying the sequence

of

construction

such as when the tank floors were to be laid the

wa lls to be started and the internal

roof

support structures were to be erected. SSEC Canada followed the tank erection

schedule as set out

by

CNRL.

7.

2.4 SSEC Canada did not provide written engineered erection procedures for the

assembly

of th

e roof suppo

rt

structure. C

NRL

did not require SSEC Canada to

provi

de

written engineered assembly procedures.

7 2.5 The SSEC Canada chief engineer who developed the erection procedure for the roof

supp

o1i

structures and specified the number si

ze

and locati

on

of the guy wires was

not a qualified professional engineer.

7.2.6 The roof support structure was a completely bolted structure using ASTM A- 307

Grade bolts without the use of wedges

or

washers. The bolted roof support

structure which was required to be flexible did not have the necessary restraints to

resist the lateral forces generated by the wind.

12

September 27. 2007


13/43

7.2 .7

7.2.8

7.2.9

7.2.10

7.2

11

7.2.11.1

Fi

le: F-536919

The number and size of guy wires that were supporting the roofsupport structure in

tanks 72-TK- IA

and 72-TK-1 B, was not designed for the static and dynamic loads

imposed by the 33 to 45 km/h wind that occurred

on

the day

of

the incident, let alone

for the maximum expected wind speed of 83 km/h, as determined by the Alber

ta

Building Code or 1

90

km/h recommended by the American Petroleum Institute.

(Attachment

A

, Photographs #

12

, #

13

, #14, #16)

There were six guy wires wrapped around girders located near the outer ring columns

to stabilize the roofsupport structure. Three

of he guy

wires were aligned in a radial

direction through

the

centre column axis; however,

the other

three

guy

wires were

significantly offset from radial alignment and

were

angled in the same direction by

14 to

24

Because

of the

offset alignment, this action would result in forces

attempting to twist the roof support structure

in

a clockwise (easterly) direction,

which is the direction of

he

eventual collapse.

Because

of

the flexible bolted structure, any

movement

caused by the wind, would

pro

vide

means to loosen the nuts on the bolts as well as intensify the twisting force

on the guy wires .

Examination

of

the roofsupport structures in tanks 72-TK-1C, 73-TK-1 and 73-TK

2 showed that many

of

the bolts used to asse

mb

le the structures were loose; so

me

bolts had become bent during tightening, or necked because the thread length was to

short. o washers

or

bevelled washers were used in the a

ss

emb ly

of

the roofsupport

structure.

On April 25 , 2007 Workplace Health and Safety

Co

mpliance contracted Anderson

Associates Consulting Engineers Inc. to examine

the

circumstances leading to the

collapse

of

he

roof

support structure in tank 72-TK-

B.

The

Professional Engineer's

report summarized the following causes:

The

collapse was primarily

the

result

of

inadequate

guy

wires used as wind bracing

on the

partially assembled flexible roof structure. As wind speeds increased, the

flexible roof structure began to load the guy wires. Due to the structure 's flexibility

and

the

unbalanced load conditions (the unbalanced geometry

of he

channel rafters

and the poor alignment

of guy

wires with

the

structure), the roof oscillated

in

the

wind. This

mo

ve

ment of

the 127 metric ton roof structu

re

imparted cyclic loading

onto the guy wires. The upwind guy w

ir

e failed first as the wire rope clips

became

o

ve

rloaded and slipped toward the floor attachment lug. Once the structure

was

able

to

move

out

of

position, it collapsed in a downwind direction-essentially blown ove

r

13

September 27, 2007


14/43

File: F-53691 9

7 .2.

11

.2 The design

of

he guy wire wind bracing was based

on

API 650 calculation methods.

These methods are inadequate for structural steel stability, although they are suitable

for their intended use tank stability). As a result, the designer, who was not a

professional engineer, determined that there was minimal need for wind bracing.

Only six 12.5 mm (half nch) guy wires were used to brace the structure against wind

loads. These were neither aligned to prevent rotation

of

he

structure

nor

sized with a

normal safety factor. When the wind speed increased, the structure began to oscillate

and the guy wires were overloaded by the inertia of the structural steel s movement.

7.2.11.3 Bracing to make the structure more rigid was not installed by the erector. This or

other temporary cross-bracing may have helped prevent

or

reduce the oscill ation that

led to the

in

ertial loa

d

More wind bracing, in tenn s

of

guy wires or structural steel

c

ro

ss-bracing, would have been required to prevent the incident.

7.

2 11

.4 The inc

id

ent was n

ot

caused by mate

ri

al failure of the wire ropes,

fi

ttings or erect ion

equipment. Testing of the wire rope and wire rope clips confin

ned

their design

capacity. Damage to the structural steel was all a result

of h

e incident The A-307

bolts used to connect the structural steel were proper strength when tested. They had

failed as the structure collapsed. t is unlikely that stronger bolts al one would have

prov id

ed the rigidity required to

pr

event the incident.

Section 8.0 APPLICABLE LEGISLATION

8 1 Occupational Health and Safety Act, Section 2 1) a) i)

Obligations o employers

8.1.1 SSEC Canada did not take reasonably practicable measures to protect the health and

safety of all the workers who were working inside the tank when the incident

occurred The tank roof support structure that co llapsed onto the workers was a

skeleton structur

e

The erection procedures

fo

r erecting the

roof

support structures

had not been prepared and certifi ed by a professional engineer

8 1 .2 Tenth Construction Company

of

Sinopec TCC) did not take reasonabl y prac

ti

cable

measures to p

ro

tect the health and safety

of th

e Electrical Consultant. The tank roof

support st

ru

cture that collapsed onto the worker was a skeleton structure. The

erecti on procedures for erecting the roofsupport structures had not been prepared and

certified by a Professional Enginee

r

Th

e El

ec

trical Consultant did not have a work

permit as a temporary

fo

reign wo

rk

er a

nd

thus should not have been working at this

work site.

14

September 27, 2007


15/43

8.2 Occupational Health

and

Safety Act, Section 3 3)

Prime

Contractor

File: F 536919

8.2. 1 CNRL did not do what was reasonable and practicable to ens

ur

e

the Act

a

nd the

regulations

we

re complied with by failing to ensure that one of their contractors had

er

ect

i

on

drawings and proced

ur

es for a skeleton

st

ructure certified by a professi

ona

l

engrneer.

8.3 Occupational Health and Safety Regulation, Section 7 1)

Availability of specifications

8.3. 1 The Occupat ional Health and Safety Code requires skele ton structures to be erected

in accordance with engineered erection procedures. SSEC Canada did not provide

engineered erection procedures.

Th

e procedures fo r the erection of the

roof

suppo1

structure were not certified by a professional engineer and the specifications were not

readily available to the workers responsible for

the

work.

The

workers

were given

only verbal instructions on the erection procedure.


and

Safety Regulation, Section 13 1) a) b)

General protection of workers

8.4. 1 SSEC Canada did not ensure that

the

engineer who developed

the

erection drawings

and procedures of he roof support structure was a professional engineer competent to

do the work, or supervised by a professional enginee

r

85 Occupational Health and Safety Code, Section 7 1)

Hazard assessment

8 5 1

SSEC

Ca

nada he ld daily too lbox meetin

gs

be fore work started. Field level risk

assessments were carried out during

the

too lbox meetings.

SSEC Ca

nada had

prepared a HSE Manual containi

ng

generic safety procedures.


and

Safety Code, Section 14 1)

Certification by a professional engineer

8.6.1

The

Code requires that skeleton structures are erected in accordance with erection

procedures certified by a profession

al

engineer. SSEC Canada did not ensure that

the

erection procedure and drawings had been certified, signed and stamped

by

a

profes

sional engineer.

5

September 27, 2007


16/43

File: F-536919

8.7

Occupational health and Safety Code, Section 46 3)

Confined space training

8.7

1 SSEC Canada

did

not

ensure that

the

worker

who was

assigned duties relating

to

confined space en

tr

y

was

trained by a competent person. The worker who had

been

de

si

gna

ted the

Co

nfined

Space Mo

nitor fo r the day

of

the

incident

was

not

aware

of

the

purpose

of the

confined space designation his

dutie

s in terms

of

mai

nta

i

ning

communi cation w ith the work

ers

in the confined space or his

dut

ies

if

an emergency

occurred. The Confined S

pace

Monitor had not been effectively trained in his

duties

and

was

n

ot compe

t

ent

to

per

fo

nn

the duties required. The Confined Space

Mon

i

tor

was not

able to

com

municate w ith the workers insi

de the

tank and was not

able to

rai

se

an alarm following the incident.

8.8

8.8. 1

8.9

8.9.1

8. 10

8.10.1

8.

11

8.1

1 1

Occupational Health and Safety Code, Section 55 1)

Confined space emergency response

SSEC Canada had an

eme

rgency respon se procedure.

Howeve

r on the day

of the

incide

nt th

e worker who had

be

en des ignated as the

Co

nfined Space Monitor was not

awa

re

of

the emergency respon

se

requirements and

was

not

capa

bl e

of

raising an

alarm or implementing an effective rescue SSEC

Canada

did

not

ensure

that the

e

mergency

res

ponse

plan included procedures

to

evacuate the confined

space

immediately.


Confined space tending worker

The wo

rk

er

who had been

de

signated as

th

e

Co

nfined Space Monitor

was

not

comp

ete

nt. SSEC Canada did

not

designate a

com

petent worker to

be

in

co

mmuni

cation with the

worke

rs in the co nfined space.


Confined space tending worker

On

the

day

of the

incident the worker who

was

the

Co

nfined

Space

Monitor did not

h

ave

a telephone or

rad

io to s

umm

on assistance.

SSEC Canada

did not ensure that

the designated

worke

r had a suitable system for s

ummonin

g assis

tanc

e.


Skeleton structures

SSEC

Ca n

ada

did not ensure that er

ec

ti

on

drawing and procedures for the erecti

on of

the roof

support structure in tank 72-

TK

IB were prepared and certified

by

a

professional

eng

ineer.

16

Septembe

r 27 2007


17/43

8. 12

Occupational Health and Safety Code, Section l90 2)

Skeleton structures

File: F-536919

8

1

2. 1

The

erection procedure

pr

epared by SSEC Canada for the erection

of

he roof

suppo1

i

stmcture in tank 72-TK-1

B

did n

ot

ensure that the structure was stable during

assembly.

8.13 Occupational Health and Safety Code, Section 300 1)

Cable clips

8.13. 1 SSEC Can

ada

did not ensure that u-bolt type clips used for fasteni ng wire rope were

installed so that the u-bolt section of the clip bears on the dead side of the rope and

the saddle

of

the clip bears on the live s ide

of

the rope.

8

1

4 Occupational Health and Safety Code, Section 306 1)

Wire rope

8.14.1 SSEC Canada did not remove from service wire rope used to support the

roof

support

structure

in

tank 72-TK- lB that had been distorted because

of

kinking where it had

been attached around girders.

Section 9.0 FOLLOW -UP ACTION TAKEN

9. 1 Alberta Employme

n

Immigration Industry

9.1. I

WHSC

issued Stop Work Orders to CNRL for the construction

of

the east and west

tank farms. WHSC issued orders for securing and dismantling the roof support

stru

ct

ures

in

the east and west tank farm. Orders were issued fo r remedial acti

on

s to

r

emove

fa

ll

en rnate1ial in tanks 1A and 1B Orders w

er

e also issued for

doc

umentation hazard assessments and for an investigation repot

i.

9. 1 2

WHSC

issued orders to SSEC Canada to provide documentation such as worker

information worker training records hazard assessment and engineeringprocedures.

Orders were also i

ss

ued to SSEC Canada to cooperate with CNRL s incident

investigation.

9. 1

3

WH

SC i

ss

ued orders to TIW to provide the tank drawing specifications assembly

instructions component testing and contact information with SSEC Canada.

9. 1.4

WHSC

i

ss

ued orders to ewfab Industries Ltd. to provide

wr

itten observations from

the disassembly of the roof support structure in tank 72-TK- 1C.

17

September 27. 2007


18/43

File: F 536919

9.1.5 WHSC issued orders to SRS Industrial Services for written observations from the

securing and the di

smantling of the

roof

support structures in tanks 73-TK 1 1 and

73-TK

1

2.

9.2 Industry

9.2.1 At this timeCN

RL

has complied with all of he written orders with the exception of

the order p

er

taining to the completion of an incident investigation report.

9.2.2 SSEC Canada complied with all of the orders written.

9.2.3 TIW complied with all of the orders written.

9.2.4 Newfab Industries Ltd. complied with all of the orders written.

9.2.5 SRS Industrial Services complied with all of the orders written.

9.3 Additional Measures

9.3

.1

o additional measures

we

re required.

Section 10 0 SI

GN TURES

Section 11 0 TT CHMENTS

Attachment A

Attachment

B

Attachment C

Attachment D

. > ' ~ A 6J c:>o7

e

S e : P 1

e ~ e i s i k ~

Date

~ Z 2 P o 7

ate ../

Photographs

Location Map

Site Layout

Sketch ofRoof Support Structure

18

September 27 2007


19/43

Photograph 1

File: F-536919

Attachment A

Page 1of22

Shows the debris field on the east side of tank 72-TK lB

after the collapse of the tank roof support structure.


20/43

Photograph 2

File: F-536919

Attachment A

Page 2

of22

Shows part

of

the debris field

on

the outside

of

tank 72-TK

lB

after the collapse. Arrow A indicates the top

of

the

welding machine where the Electrical Consultant was

standing when he was struck by the collapsing steel. Arrow

B

indicates where the Electrical Consultant's body was

found.


21/43

Photograph #3

File: F-536919

Attachment A

Page 3 of22

Shows the interior

of

tank 72-TK- l B after the collapse of

the roof support structure. This image was computer

generated from several photographs. Arrows A indicate

one of the vertical columns in the outer ring, and the base

where it was standing before

the

collapse. Arrows B

indicate one

of

the vertical columns in the inner ring and its

base.


22/43

File: F-536919

Attachment A

Page 4 of22

Photograph #4 Shows the interior of tank 7 -TK-lB after the collapse of

the roof support structure. Arrow A indicates the centre

support column. Arrow B indicates the hard hat that was

worn

y

the Scaffolder.


23/43

Photograph #5

File: F-536919

Attachment A

Page 5

of22

Shows the interior of tank -

TK-lB

after the collapse of

the

roof

support structure. Arrow

A

indicates the welding

machine partially dislodged from the

tank wall that the

Electrical Consultant was standing on, and Welder 1 was

working in, at the time

of

the incident. Arrow B indicates

the welding machine that fell from the tank wall, that

Welder 2 was working in.


24/43

Photograph #6

File: F-536919

Attachment A

Page 6 of22

Shows a closeup view of the welding machine that Welder 2

was working in.


25/43

Photograph #7

File: F

36919

Attachment A

Page 7 of

Shows a closeup view of the welding machine that the

Electrical Consultant was standing on, and that Welder 1

was working in.


26/43

Photograph 8

File: F-536919

Attachment

A

Page 8 of22

Shows part of the collapsed structure from tank 72-TK-lB,

showing one of the % inch bolts that were used to bolt the

components of the roof support structure together.


27/43

Fil

e

F-536919

Attachment

A

Page 9

of22

Photograph 9 Shows a sheared

4

inch bolt on the ground to the east

of

tank 72-TK

-lB.


28/43

File: F-536919

At

tachment A

Page 10 of

Photograph #10 Shows the bolt also shown in photograph 9. The markings

on the bolt head indicating the specification of the bol

t

A-

307-B, can be seen.


29/43

File: F-536919

Attachment A

Page of22

Photograph #11 Shows the completed roof support structure in tank 72-TK

lA before it also collapsed. The roof structure that

collapsed in tank 72-TK-lB was identical to this. Arrow

indicates one of the support cables.


30/43

File: F-536919

Attachment

A

Page 12

of22

Photograph #12 Shows a closeup

of

one

of

the support cable top connections

on tank 72-TK

1A

Arrow

A

indicates where the support

cable has been secured back onto itselfusing a screw pin

shackle. Arrow

B

shows the top connection of one of the

cables that had been used to support the vertical column

during the erection

of

the roof support structure. This cable

had not been removed after the assembly

of

the structure

was completed.


31/43

File: F-536919

Attachment

A

Page

3

of22

Photograph

3

Shows the top connection of another support cable on tank

72-TK- lA. Arrow indicates where the cable is kinked as it

passes over the top plate of the column.


32/43

File: F-536919

Attachment

A

Page

14of22

Photograph 4 Shows a beam from tank 72-TK-lB after the collapse

of

the

roopf support structure. The top end of one of the support

cables is still attached to the beam. Arrow indicates where

the cable has been kinked and distorted as it passed through

the shackle.


33/43

File: F

5

36919

Attachment

A

Page 15 of22

Photograph

15

Shows the partially completed roof structure in tank 72-TK

l

C.

The cables used to support the vertical columns can

be

seen. The centre column and the inner ring of6 columns

have been erected, the beams have been installed joining the

inner ring, and some

of

the radial purlins have been

installed.


34/43

File: F-536919

Attachment A

Page 16

of22

Photograph #16 Shows the base

of

the centre column in tank 72-TK-lC. The

come-alongs tensioning the cable supporting the columns

can be seen. Arrow A indicates a cable that has been

clamped correctly, with the saddle clamps installed so that

the saddles are on the live side

of

the cable. Arrow B

shows one that has been made up incorrectly, with t

he

saddles on the dead side of the cable.


35/43

File: F-536919

Attachment A

Page 17of22

Photograph 17 Shows tanks

73

-TK-l land 73-TK

1

2 on the east tank farm.

These tanks are smaller than the tanks on the west tank

farm. The roof support structures consist of a centre colwnn

and one ring of6 columns. The roof support structure

installation has been completed and the support cables can

be

seen.


36/43

File: F-536919

Attachment A

Page 18of22

Photograph # 8 Shows the debris field on the east side of tank 72-TK-lA

after the roof support structure in this tank also collapsed.


37/43

.....

File: F-536919

Attachment A

Page 19 of22

Photograph #19 Shows the collapsed roof support structure on the east side

of

tank 72-TK-lA. t can be seen that several tank wall

sections were broken off this tank during the collapse.


38/43

File: F-536919

Attachment A

Page 20 of22

Photograph #20 Shows an intact orbital welding machine on the inside of a

tank wall. A welder working inside the welding machine

would be welding the horizontal seam indicated by the

arrow.


39/43

.

File: F-536919

Attachment A

Page

21 of

22

Photograph

21

Shows an inta

ct

orbital

we

lding machine seen from outside

the tanlc The work platform on the top of the welding

machine can

e

seen. The Electrical Consultant was

standing on the top work platform of

a sim

il

ar

we

lding

machine at the time of the incident.


40/43

File: F-536919

Attachment A

Page 22 of22

Photograph 22 Shows the lower end of one of the cables supporting the

roof

support structure in Tank 72-

TK-lB

after the collapse

of he structure.


41/43

ort

Ma aii

File Number: F-536919

Attachment: B

Location Map

Not

t

Scale

N

s


42/43

Sulphur

Recovery:

Coker Diluent Reco ery

Cogeneratlon Plant and Utilities

N

WestTank Farm

w s

Ad

min Warehousing

\ To Aerodrome 5km

File Number: F 369 9

Attachment:

Site Layout

Not to Scale

C

Camp3

Lodge

astTank Farm

Hydrogen Plant

Hydrotreating

Heat

Integration

\Froth Treatment

To South Mine

Mine Maintenance and

Administration Facilities

PllSlse

D

Phase: D


43/43

.

GUY

WIRES

1

OUTER

RING

SUPPORT

COLUMN

TANK

SHELL

TANK SHELL

ELEV TION

INNER

RING

SUPPORT COLUMN

CENTRE SUPPORT

COLUMN

GUYWIRES

F536919

Attachment D

Sketch of

roof

support

structure

Not to scale

OUTER RING

GIRDERS

INNER

RING

GIRDERS

Documents

OHS Worker Fatalities Report