Variable Springs Catalogue

7/28/2019 Variable Springs Catalogue

1/17

Variable SpringSupports

Section 2


2/17

Variable spring support units are devices used to support pipework which is subject tovertical displacement because of temperature changes or subsidence. It isrecommended that a variable spring support unit only be used when the load variation

is less than 25% from cold to hot load and that the displacement is small, up to 50 mm.Where the conditions are out of this criteria a QUALITY PIPE SUPPORTS constantspring support should be considered. Practical and technical advice is available fromQUALITY PIPE SUPPORTS.

All units are pre-set to their cold load. Each unit will have been checked through its totalworking range and its required working range. The variable spring unit will be tested ona specialised test rig which is calibrated back to a national standard.

The variable spring support finish is available as follows:

Hammer finish paint Hot dip galvanised Customer specific paint finish.

Spring coils are plastic coated on standard galvanized units.

Q.P.S. variable spring units are produced in high quality carbon steel, but we are ableto offer units from austenitic stainless steel and various alloy steels where required.

Where a spring unit is required which is not covered by the Q.P.S. range, our technical

department will design a unit for your particular requirement.

All Q.P.S. variable spring support units are capable of supporting pipework that can besubjected to hydrostatic test loads up to two times the working load of the unit.

ORDERING

When ordering please specify:1. Q.V. number, e.g. (Q.V. 2)

2. Model, e.g. (A, B, D etc.)

3. Size (taken from selection table)

4. Thread details

5. Vertical movement and direction of movement, e.g. cold to hot, 16 mm up

6. Preset load (Q.P.S. can calculate this for you given the information as above)

7. If Hydrostatic stops are required

8. Protective finish

9. Marking (identification) number10. Distance between rod centres and total load for model G.

Page 31

DESCRIPTION


3/17Page 32

HOW TO SELECT THE APPROPRIATE VARIABLE SIZE (0-22)INFORMATION NEEDED:SUPPORTED LOAD = Load calculated when pipe is in the hot position

including insulation, contents, weight of pipe andancillary equipment.

INITIAL SELECTION = Select size by plotting load in table.TRAVEL UPOR = Distance pipeline moves and in what direction.TRAVEL DOWNPRESET LOAD = Calculate by multiplying the spring rate from the table

by the TRAVEL UP (+) or TRAVEL DOWN (-) and addingto SUPPORTED LOAD.

Example Size 8 Supported Load = 366 kgQV1 Travel Up 3mm

x Spring Rate 5.4 = 16.2 kgPreset Load = 382.2 kg

SELECTION PROCEDURE:After initial selection in the support table and calculation of preset load check the preset load and

travel are within range shown for size.Then check load change at cold position is within 25% of hot load as follows:

PRESET LOAD 382.2x 100 (using the above example) x 100 = 104.4%

SUPPORTED LOAD 366

Acceptable, if not rework calculations using QV2 or QV3. Spring rates if still not within 25%consider constant load support. Look up 366 Kg in table, located in Column 8 (Spring Size), movedown 3mm as travel is up, to check still within working range. If it is then size is correct, if not,move up or down a size and repeat selection.

EXAMPLE WHERE FIRST SELECTION IS INCORRECT:

Supported Load = 366

Travel Up 50mm Preset Loadx Spring Rate 5.4 = 270 = 173%

Supported LoadPreset Load = 636

TRY QV3

Supported Load = 366

Travel Up 50mm Preset Load 431x Spring Rate 1.3 = 65 = 118%

Supported Load 366

Preset Load = 431

Acceptable and within range so selection would be QV3 Size 8 Preset Load 431, Hot Load 366.

NOTE: The preset load is in over travel, which is acceptable in this case. Do not select when hotload is in over travel. The supports have been designed to perform best inside the working range.

TO CALCULATE ROD TAKE OUT:

Look up minimum rod take out in the table for model size and type selected, this is the dimensionin the minimum load position. Then determine on working range scale where the preset load ispositioned or add to dimension shown in tables, using the above as an example.

QV3 say Model A Size 8 look up table = 463mmPreset Load at 431 read on scale = 141mmRod take out = 604mm

TO CALCULATE LOADED LENGTH OF MODEL F:

Look up maximum loaded length in table for model, size and type selected. Then determine onworking range scale where preset load is positioned and subtract from dimension shown.

Example QV2 Size 16 Present Load = 3506.5 KgMaximum dimension from table = 543mmPreset Load read on scale at 42Loaded length 501mm

SELECTION PROCEDURE


4/17Page 33

Variable Spring SupportsDiagrams and Tables


5/17


6/17


7/17

Page

36

O

W A

LOADED

LENGTH

Y

P.C.D.

W

MODEL

A

SEE MODEL F FO

MODEL H

OTHER DETAILS

RADIUS T

CUSTOME

REQUIRE

ROD

TAKE

OUTA

O

W

D DIAB

T

C

Rod Take Out

(at Load Position)

TLOAD FLANGE

(P.T.F.E. SLIDER OPTIONAL)

MODEL B

BEFORE SELECTING THE SIZEWORKING LOAD MUST BE HALVEDNOTE : ON TYPE G UNITS THE

O

W

D DIA

ROD

TAKE

OUT

W

MODEL FMODEL A

MODEL E

O

ROD

TAKE

OUT

A

W

MODEL GREQUIRED

X

N

AROD

TAKE

OUT

VARIABLE SPRING SUPPORTS

FIG. QV1


8/17


9/17

Page

38

O

W A

LOADED

LENGTH

Y

P.C.D.

W

MODEL

A

SEE MODEL F FOR

MODEL H

OTHER DETAILS

RADIUS TO

CUSTOME

REQUIREM

ROD

TAKE

OUTA

O

W

D DIAB

T

C

Rod Take Out

(at Load Position)

TLOAD FLANGE


MODEL B


O

W

D DIA

ROD

TAKE

OUT

W

MODEL FMODEL A

MODEL E

O

ROD

TAKE

OUT

A

W

MODEL GREQUIRED

X

N

AROD

TAKE

OUT


FIG. QV2


10/17


11/17

O

W A

LOADED

LENGTH

Y

P.C.D.

W

MODE

A

SEE MODEL F FO

MODEL H

OTHER DETAILS

RADIUS T

CUSTOM

REQUIRE

ROD

TAKE

OUTA

O

W

D DIAB

T

C

Rod Take Out

(at Load Position)

TLOAD FLANGE


MODEL B


O

W

D DIA

ROD

TAKE

OUT

W

MODEL FMODEL A

MODEL E

O

ROD

TAKE

OUT

A

W

MODEL GREQUIRED

X

N

AROD

TAKE

OUT

Page

40


FIG. QV3


12/17


13/17

O

W A

LOADED

LENGTH

Y

P.C.D.

W

MODE

A

SEE MODEL F FO

MODEL H

OTHER DETAILS

RADIUS T

CUSTOM

REQUIRE

ROD

TAKE

OUTA

O

W

D DIAB

T

C

Rod Take Out

(at Load Position)

TLOAD FLANGE


MODEL B


O

W

D DIA

ROD

TAKE

OUT

W

MODEL FMODEL A

MODEL E

O

ROD

TAKE

OUT

A

W

MODEL GREQUIRED

X

N

AROD

TAKE

OUT

Page

42


FIG. QV4


14/17


15/17Page 44

INSTALLATION INSTRUCTIONS

QUALITY PIPE SUPPORTS

VARIABLE SPRING UNITSVariable Spring Units are pre-set to a cold load position before despatch from our works.

The pipe system being supported in service would be either :

(a) dry system

(b) wet system

In the event that the system is 'dry' in service but has to undergo a hydraulic test prior to

service the spring units should be ordered with down travel hydrostatic test stops which

would remain in position until the hydraulic test has been carried out.

In the event that the system is 'wet' in service then the standard pre-set stops which set theunits to 'wet load' are all that is necessary.

Once removed the pre-set stops on all units should be retained in case of a requirement for future

use. If it becomes obvious that an incorrect load is being applied to any supports in the system it

is advisable to contact our sales support team who would be pleased to give advice.

To Install Spring Units - Type A,B,C.

The spring unit is fitted between the Pipe/Duct/Bracket to be supported and the steelwork

above the unit. The hanger rod coming up from the Pipe Clamp/Duct/Bracket is connected to

the turnbuckle which is fitted to all these types of spring units.

Rotation of the turnbuckle transfers the pipe load to the spring unit thus allowing withdrawal

of the pre-set stops. No further adjustment should be required unless it becomes obvious thatincorrect loads are being applied to supports in the system.

To Install Units Type D and E.

Both of these units are mounted on top of the steelwork.

Type D

The hanger rod passes through the unit and is secured to the spring unit at the top of the load

tube by 2 nuts.The hanger rod should be of adequate length and threaded sufficiently to take

into account any deviation in pipe or duct elevation since these units are not supplied with a

turnbuckle. Adjustment of the 2 nuts transfers the load to the spring unit thus allowing

withdrawal of the preset stops.

Type E

The hanger rod passes through the Spring units and is secured with 2 nuts which prevent it

passing through the Spring pressure plate. Adjustment in length is provided by a turnbuckle

at a convenient situation in the hanger assembly.

Rotation of the turnbuckle transfers the load to the spring unit allowing withdrawal of the pre-

set stops.

To Install Spring Units Type F, H & K

These units are base mounted and should be aligned directly below the point of support. Theheight of the load flange is adjusted to contact the lower surface of the support point by

rotation of the adjustment nut on the load column. Further rotation of this nut will transfer the

load onto the Spring unit and the pre-set stops can then be withdrawn.



16/17Page 45

To Install Spring Units Type F(A)

These units are base mounted and should be aligned directly below the point of support. The

height of the load flange is adjusted to contact the lower surface of the support point by

rotation of the adjustment nut on the load column. The lower of the two sets of "Red Painted"

adjusting nuts(A) can be wound clear of the pressure plate at this time, or after the HydrostaticTest (if required) has taken place. Further rotation of the adjustment nut on the load column

will transfer the load onto the spring unit. The upper of the two sets of "Red Painted" adjusting

nuts (B) can then be wound clear of the pressure plate.eg.(towards the locknut(C)).

To Install Spring Units Type G

The units are fitted with turnbuckles so that the hanger rods which having been previously

connected to the steelwork above can be inserted into them. The rotation of the turnbuckles

transfers the load to the spring units. When the load is correctly supported the pre-set stops

can be withdrawn.

Inspection During Operation

Shortly after commissioning the support should be examined to ensure correct travel has

been achieved in the hot position. If the load plate is against the stop at either end of the scale

an investigation should be made at once. Subsequently the support should be examined at

regular intervals to ensure no change has occurred either in application or condition. The

frequency of examination intervals will depend on the environmental and operating

conditions and will range from annual examinations for land based dry atmospheres to

maybe monthly frequency in hostile offshore conditions with the possibility of salt

contamination.

MaintenanceIf an excessive build up of foreign matter or corrosion is observed it is important that the

Spring support is cleaned either by hand or with a pressure washer to ensure uninhibited

operation.



17/17

NOTES

Documents

Variable Springs Catalogue