Thickness Monitoring Location Guide.pdf

8/10/2019 Thickness Monitoring Location Guide.pdf

1/16


2/16

ConocoPhillips Indonesia

Maintenance Engineering & AssetIntegrityManual

TITLE DOCUMENT NUMBER REV DATE PAGE

Thickness Monitoring Location Guide COPI-OPR-OM-MA-00086 0 27 May04 2 of 16

Paper Copies are UNCONTROLLED Check with Document Control for latest available Revision COPICONTROLLED copies should be RED stamped

REVISION CONTROL SHEET

LATEST REV DATE ISSUED PREPARED REVIEWED APPROVED COMMENTS


3/16


Maintenance Engineering & AssetIntegrity

Manual


THICKNESS MONITORINGLOCATION GUIDE

COPI-OPR-OM-MA-00086 0 27 May 04 3 of 16


TABLE OF CONTENTS

1. INTRODUCTION ....................................................................................................0

2. PURPOSE.............................................................................................................. 0

3. SCOPE................................................................................................................... 0

4. RESPONSIBILITIES .............................................................................................. 0

5. PREPARATIONS GENERAL.............................................................................. 0

6. PREPARATIONS PIPING ................................................................................... 0

7. PREPARATIONS VESSELS............................................................................... 0

8. PREPARATIONS STORAGE TANKS ................................................................ 0

APPENDIX A: DEFINITIONS AND ABBREVIATIONS ..................................................0


4/16



Manual





1. INTRODUCTION

This document is to provide guidance to the Asset Integrity Engineer or the Inspection Engineerwhen establishing or reviewing locations of thickness monitoring locations (TMLs). It is applied toany process equipment that is subject to thinning either from corrosion or erosion. It is notapplicable to finding damage from other mechanisms such as Stress Corrosion Cracking whichrequires a substantially different inspection program. Corrosion resistant piping and vessels aregenerally exempt from thickness monitoring except where erosion is identified as a potentialdamage mechanism.

2. PURPOSE

This Thickness Monitoring Location Guideprovides instructions for locating sites for performingultrasonic thickness measurements on piping, pressure vessels and tanks systems when conductingan on-stream thickness survey. The TML locations should be designed to pick up the areas ofhighest predicted or expected corrosion rates. The intention is to do more thickness monitoring inareas where corrosion is likely and a lesser extent when corrosion is unlikely. To achieve this the

Asset Engineer must understand the applicable corrosion mechanisms and the physical features,such as injection points, that might cause localized corrosion. The inspector must also understandthat the TML location is only a starting point, if thinning is found then the inspector shall continuescanning outside the TML to characterize the entire extent of thinning.

3. SCOPE

This procedure applies to ultrasonic thickness measurements taken on piping systems, vessels andtanks at ConocoPhillips Indonesia (COPI).

4. RESPONSIBILITIES

The Asset Integrity Engineer in cooperation with the Inspection Engineer is responsible for ensuringproper location for ultrasonic measurements in accordance with this procedure and other applicablecodes and specifications.

5. PREPARATIONS General

5.1 Obtain Process Flow Diagrams, Process and Instrumentation Diagrams and, if possible,System Isometric drawings for piping. Obtain vessel or tank general arrangement drawingsas applicable. Identify materials of construction, pipe classes and insulations specifications.Identify sand production that may lead to erosion. Determine predicted corrosion rates forthe process fluid.

6. PREPARATIONS Piping

6.1 Verify personnel performing Ultrasonic Thickness Measurements are qualified.

6.2 Ensure all instruments to be used have been properly calibrated.


5/16



Manual





6.3 Before starting the inspection, the Inspector Engineer should review the results of theprevious inspections and check with the operators in order to determine if the equipment hasoperated under any unusual conditions, such as high/low temperature excursions,overpressure, or any leakage.

6.4 SPECIAL TOOLS AND EQUIPMENT

None

6.5 REFERENCESAPI 570: Inspection, Repair, Alteration, and Rerating of In-Service Piping Systems

6.6 PROCEDURE

NOTE

Thickness measurement locations should be identified on the applicableinspection drawing. New locations not previously inspected should be addedto the drawing when required.

6.7 Insulated Piping

Insulated piping is only separated out from Non-insulated piping because of the need forspecial inspection windows and the need to look for Corrosion Under Insulation (CUI). Foreach TML a window will have to be cut into the insulation. Ideally, a replaceable plug will be

inserted into this window to simplify future inspections. If this is not possible the insulation mustbe restored after inspection.

Once the lines have been established to be subject to thinning corrosion, either by theCorrosion Engineer or from a RBI study, TMLs should be established at the followinglocations:

On the center line of outer radius of elbows. The inspection point should be in line with thefluid flow and will cover the target zone where entrained particles would be expected tostrike the inside of the elbow. This is generally the most severely attacked area from botherosion and corrosion. An additional TML shall be located one pipe diameterdownstream from the elbow and on the same side of the pipe as the TML on the elbow.In cases where severe erosion is likely, an additional TML on the opposite side of thepipe at the same distance from the elbow should be established.

A pipe run in a known corrosive service should have TMLs at least every 5 meters. If thecorrosion is known to be due to condensations then it is logical to have TMLs only alongthe bottom of the pipe but where corrosion is more generalized it is good practice tohave TMLs located at 90-degree intervals around the pipe. In cases where severeerosion is likely an additional TML on the opposite side of the pipe at the same distancefrom the elbow should be established.

Measurement points should also be assigned to areas with unusually high historical orpredicted corrosion rates.


6/16



Manual





If further inspection is required due to corrosion rates or if the piping is approaching theretirement thickness, additional inspection holes will need to be provided.

Additional inspection windows should be established at low points to look for corrosionfrom water condensation or drop out and to look at the external condition of the pipe forCUI.

Obtain thickness measurements in accordance with the approved Inspection Procedure forUltrasonic Thickness Measurement.

6.8 Non-Insulated Piping

Once the lines have been established to be subject to thinning corrosion, either by theCorrosion Engineer or from a RBI study, TMLs should be established at the followinglocations:

On the center line of outer radius of elbows. The inspection point should be in line with thefluid flow and will cover the target zone where entrained particles would be expected tostrike the inside of the elbow. This is generally the most severely attacked area from botherosion and corrosion. An additional TML shall be located one pipe diameterdownstream from the elbow and on the same side of the pipe as the TML on the elbow.In cases where severe erosion is likely, an additional TML on the opposite side of thepipe at the same distance from the elbow should be established.

A pipe run in a known corrosive service should have TMLs at least every 5 meters. If the

corrosion is known to be due to condensations then it is logical to have TMLs only alongthe bottom of the pipe but where corrosion is more generalized it is good practice tohave TMLs located at 90-degree intervals around the pipe. In cases where severeerosion is likely an additional TML on the opposite side of the pipe at the same distancefrom the elbow should be established.

Measurement points should also be assigned to areas with unusually high historical orpredicted corrosion rates.

If further inspection is required due to corrosion rates or if the piping is approaching theretirement thickness, additional inspection holes will need to be provided.

Additional inspection windows should be established at low points to look for corrosionfrom water condensation or drop out and to look at the external condition of the pipe forCUI.

Obtain thickness measurements in accordance with the approved Inspection Procedure forUltrasonic Thickness Measurement.

6.9 Injection Point Inspection

Injection points are generally areas of increased risk of corrosion, either from condensation orincomplete mixing of chemicals. For injection points that use a quill, the TMLs should belocated at 2 and 4 pipe diameters away from the pipe in the downstream direction anddistributed at 90 degree intervals around the pipe


7/16



Manual





7. PREPARATIONS Vessels





None

7.5 REFERENCES

API 510: Pressure Vessel Inspection Code, Maintenance Inspection, Rating, Repairand Alteration of Pressure Vessels

ASME Boiler and Pressure Vessel Code, Section VIII, Div. 1.

7.6 PROCEDURE

NOTE

Thickness measurement locations should be identified on the applicableinspection drawing. New locations not previously inspected should be addedto the drawing when required.

7.7 Insulated Vessels

Where specified in an equipment specific analysis such as a RBI study, the TML locationsshall be located per the study. Where no specific studies have been made, one TMLminimum should be assigned to each pressure-containing component. For example, eachhead, each shell diameter transition and all accessible nozzles shall be checked.

It is preferred to have a TML in each shell section if accessible.

TMLs should also be assigned to areas of known or predicted high corrosion rates.

TMLs shall be located on drain nozzles.

TMLs shall be located on any water boots on the bottom and at the normal water line.

If further inspection is required due to abnormal corrosion rates, or if the vessel isapproaching the retirement thickness, additional inspection insulation holes will need to beprovided.


8/16



Manual





For each TML a window will have to be cut into the insulation. Ideally, a replaceable plug willbe inserted into this window to simplify future inspections. If this is not possible the insulationmust be restored after inspection.

7.8 Non-Insulated Vessels

As above, where a specific study provides locations for TMLs then that study shall befollowed. Otherwise, one TML minimum should be assigned to each pressure-containingcomponent. For example, each head, each shell diameter transition and all accessiblenozzles shall be checked.

It is preferred to have a TML in each shell section if accessible.

TMLs should also be assigned to areas of known or predicted high corrosion rates.

TMLs shall be located on drain nozzles.

TMLS shall be located on any water boots on the bottom and at the normal water line.

8. PREPARATIONS Storage Tanks





None

8.5 REFERENCES

API-653 Tank Inspection Code

8.6 PROCEDURE

NOTE

Thickness measurement location should be identified on the applicableinspection drawing. New locations not previously inspected should be addedto the drawing when required.

8.7 Shell -Course "A" of non-Insulated Tanks Using A Grid System


9/16



Manual





NOTE

A letter shall designate each course: A for the bottom course, B for the second course andso on.

All points on shell to be 2 from full seams (partial door sheet and patch plate seamsnot inclusive, unless through adjoining weld seam). If thickness readings vary morethan .01", the area will be scanned and the average thickness will be recorded.

8.7.1 A course starting point is, facing tank from outside, left of first vertical weld seam leftof the north most plate. (This area is normally identified by a man-way or tank piping.)

Pipe+ Data PointPosition Description Location Description

8.7.2 2 left of vertical seam, 2 above chime weld. A1 BTM RT

8.7.3 2" above chime, midpoint left around shell plate. A2 BTM CN

8.7.4 2 above chime, 2 right of next vertical weld seam. A3 BTM LF

8.7.5 2 right of vertical weld, 2 down from top platehorizontal weld. A4 TP LF

8.7.6 2 below horizontal weld seam, directly below each

vertical weld seam from course B. **a.m.a.n. TP JCT

8.7.8 2 below horizontal weld seam, 2 left of verticalweld seam, above 9.1.2. TP RT

8.7.9 Pick up nozzles in this plate, right to left; top to bottom if TP MWvertically aligned. Include nominal size in location description; MTB MW 4NOZtop, bottom, and both sides on thickness on nozzles and on man-ways.

8.7.10 Continue on the next shell plate to the left in successivenumbering, as in 9.1.2 through 9.1.7 above.

8.8 Shell -Course "B" of non-Insulated Tanks Using A Grid System

NOTE

Course B starting point is left of first vertical weld seamto left of course A starting seam.


8.8.1 2 left of seam, 2 above course A horizontal weld. B1 BTM RT

8.8.2 2 above course A horizontal weld, directly above courseA vertical junctions. **a.m.a.n. BTM JCT


10/16



Manual





8.8.3 2 above course A, 2 right of next vertical weld seam. BTM LF

8.8.4 Pick up all nozzles in this plate, right to left, and top to TP BTMbottom if vertically aligned. Include nominal size in location BTM MW 4NOZdescription; top, bottom, and both sides on thicknesses onman-ways and nozzles..

8.8.5 Continue on shell plate to left in successive numbering, as inPosition Description 9.2.1 through 9.2.3 above.

8.8.6 More data points may be accessible on B course as stepsare ascended. Effort should be given to obtaining thickness

readings at junction welds, when possible.

Add itional Shell Courses

Course C and each succeeding course should have starting points at bottom of respectivecourses where accessible from steps. Effort should be given to obtaining thickness readingsat junction welds, when possible.

The top 2 of top course is an area of critical importance on tanks with cone roofs. This areashould have data points every two feet (2), starting nearest steps and continuing around tank,where accessible from, and in direction of, steps.

**a.m.a.n.- as many as necessary. Some plates may not have any intersecting welds. Others may have several.Include all horizontal-vertical junctions.

8.9 Cone Roof of Insulated and non-Insulated Tanks Using A Grid System

8.9.1 The roof data points will be designated by a letter; R. Critical portions of roof arefrom platform to gauging hatch where Operations and gauging personnel walk. Thisarea will be inspected on a 2 grid, or Walkway, a minimum of 3 points (4) wide.Grid starting point is determined by best fit of the Walkway from platform to gaugehatch. Each 2 row of grid will be designated by successive Steps (see AttachmentB).

8.9.2 Remaining portions of roof shall be shot in an X and 0 pattern. This X will be inan alignment such that one leg is straight from platform/step attachment over center ofroof. The other leg of the X shall lay perpendicular to the first. One data point

should be defined at each joint junction, i.e., roof course changes, plate changes, orcombination of the two (case #1 in Roof Example drawing). If the first X lies suchthat a leg parallels the roof courses, an additional measurement should be taken atcenter of each plate (case #2 in Attachment B). The 0 pattern should be made at theouter most diameter of the tank roof. This area should incorporate at least two roofpatterns wide the full circumference of the roof at the T seams of the roof.

8.9.3 The extent of the X pattern will therefore be determined by the diameter andalignment of roof to steps and platform. Thickness measurements should be taken oneach end of plate as the line passes the course, and each junction near the line.



11/16



Manual





(for each data point in grid row titled STEP)

1) 2 off platform. Facing gauge hatch, the left-most point of grid.R1, R2, R3 STEP 1

2) 2 step toward gauge hatch, the left-most point of grid.R4, R5, R6 STEP 2

3) Continue on the roof using X pattern in successive numbering.

4) Continue using the 0 pattern starting at the left side of the stairway platform continuingclockwise around the tank. The numbering system should alternate from the outer course Tseam location to the inner until the complete circumference of the tank has been completed.

8.10 Shell -Course "A" of Insulated Tanks Using A Grid System

NOTE

Each course is designated by a letter; A for bottom course, B for second course, etc.

All points on shell to be 2 from bottom (chime) weld. Acourse starting point is left of bottomstep of ladder when facing tank from outside. For intersecting ladders, start with shell datapoint to left of ladder attachment point. Continue in clockwise (left) direction.

With insulated tanks, shell course sizes might take some guesswork for size, or somepreliminary work may need to be done. Since vertical welds are generally not accessible,each course should be graded individually. That is, additional data points may be needed to

confirm any variances in measurements. This will be a judgment call of the inspector at timeof inspection. The approximate distance between data points will be determined by the

inspector, generally not to exceed a maximum of 20to 30. The number of measurements oneach course should be enough to give representative coverage.


8.10.1 2 above chime weld. A1

8.10.2 Pick up nozzles in this plate, right to left; top to bottom if TP MWvertically aligned. Include nominal size in location description; BTM MWwith top and bottom thicknesses on man-ways. TP 4NOZ

8.10.3 Continue on the next data point to the left in successivenumbering.

8.11 Shell -Course "B" of Insulated Tanks Using A Grid System

NOTE

Course B starting point is above or left of the first data point of course A.



12/16



Manual





8.11.1 2 above course A horizontal weld. B1

8.11.2 Include all nozzles in this plate, right to left, and top to bottom TP MWif vertically aligned. Include nominal size in location BTM MWdescription; - top and bottom thicknesses on man-ways. TP 4NOZ

8.11.3 Continue on shell plate to left in successive numbering.

8.11.4 Additional data points may be accessible on B course as stepsare ascended.

Add itional Shell Courses

Course C and each succeeding course should have a starting point at bottom of respectivecourses where accessible from steps.

Where accessible, top 2 of top course is an area of critical importance on tanks with coneroofs. This area should have data points every two feet (2), starting nearest steps andcontinuing around tank, where accessible from, and in direction of, the steps.

9.0 ATTACHMENTS

Attachment A - Examples Of Shell Location Descriptions Non-Insulated TanksAttachment B - Examples Of Roof Location Descriptions Insulated And Non-Insulated TanksAttachment C - Examples of Shell Location Descriptions Insulated TanksAttachment D - Revision History


13/16






ATTACHMENT AEXAMPLES OF SHELL LOCATION DESCRIPTIONS NON- INSULATED TANKS

A1/BTM RTA2/BTM CNA3/BTM LFA4/TP LF

A5/TP JCTA6/TP JCTA7/TP JCTA8/TP RTA9/TP MW

A10/BTM MWA11/6NOZA12/BTM RT...B1/BTM RTB2/BTM LFB3/BTM RT...B85/BTM RT

B86/BTM JCTB87/BTM JCTB88/BTM LFB89/TP JCT...


14/16






ATTACHMENT BEXAMPLES OF ROOF LOCATION DESCRIPTIONS - INSULATED AND NON-INSULTED TANKS


15/16






ATTACHMENT CEXAMPLES OF SHELL LOCATION DESCRIPTION - INSULATED TANKS

A1 / BTM RTA2 / BTM CNA3 / BTM LFA4 / BTMA5 / 4NOZA6 / BTM...

A44 / BTM.

.

.B1 / BTMB2 / BTMB3 / BTM...B27 / BTMB28 / MID...

C1 / BTMC2 / MID. . . .


16/16



Manual



COPI-OPR-OM-MA-000ZZ 0 03 May 04 16 of 16


APPENDIX A: Defini tions and Abbreviations

TP TopMW ManwayBTM BottomNOZ NozzleTML Thickness monitoring location

Documents

Thickness Monitoring Location Guide.pdf