PTP-1 F-Type Variable Spring Assemblies

PTP-1 F-Type Variable Spring Assemblies

These PTP-1 F-Type variable spring assemblies fabricated from A-36 carbon steel, were custom designed to accommodate a height of 11-11/16″ while keeping the same spring rate. The F-Type variable is used to support the pipe from below and are typically mounted to concrete pads via anchor bolts or welded to structural steel. The variables are designed for loads up to 6,500 lb. and a total upward travel of 5/16″.

PTP-1 F-Type Variable Spring Assemblies

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48" Diameter Stainless Steel Glycol Makeup Tank Fabricated By Our Sweco Fab Division.

48" Diameter Stainless Steel Glycol Makeup Tank

This Glycol Makeup Tank is fabricated entirely from ASTM A240-304 stainless steel and is rated for 0 psig at 150°F. The tank has a 1,000 gallon capacity and measures 48″ I.D. x 10′-8″ seam-to-seam. The stand pictured behind is also fabricated from stainless steel and measures 11′ high. The customer ordered six additional units and all the Makeup Tanks underwent leak testing prior to shipment.

48" Diameter Stainless Steel Glycol Makeup Tank

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How do you install an expansion joint?

The necessary steps for installing all expansion joints shall be pre-planned. The installers shall be made aware of these steps as well as the installation instructions furnished by the manufacturer. The most critical phases of the expansion joint installation are as follows.

  • Care shall be exercised to prevent any damage to the thin bellows section, such as dents, scores, arc strikes and weld spatter.

  • No movement of the expansion joint (compression, extension, offset, rotation and especially torsion) due to piping misalignment, for example, shall be imposed which has not been anticipated and designed into the movement capability of the expansion joint. If such movements are imposed, they can result in system malfunction, damage to the bellows or other components in the system. Specifically, cycle life can be substantially reduced, forces imposed on adjacent equipment may exceed their design limits, internal sleeve clearances may be adversely affected, and the pressure capacity and stability of the bellows may be reduced.

  • Any field pre-positioning shall be performed in accordance with specific instructions which include both the direction and magnitude of the movement.

  • Anchors, guides and pipe supports shall be installed in strict accordance with the piping system drawings. Any field variances from planned installation may affect proper functioning of the expansion joint and must be brought to the attention of a competent design authority for resolution.

  • The expansion joint, if provided with internal sleeves, shall be installed with the proper orientation with respect to flow direction.

  • After the anchors or other fixed points are in place and the piping is properly supported and guided, the expansion joint shipping devices should normally be removed in order to allow the expansion joint to compensate for changes in ambient temperature during the remainder of the construction phase.

What are embed plates?

Embedplates are metal components which are essentially set-in foundation elementssuch as concrete floors, piers, etc. They provide an attachment point forwelding support components in position or for the addition of sliding plateelements to permit movement along the surface of the embed plates.

Two 240 inch x 12 inch x 1/2 inch embed plates for a concrete reinforcement application
Embed Plates

Regarding various types of pipe clamp devices, are these devices also suitable for use with polymer material pipe?

Yes, pipe clamps are suitable for polymer materialpipe, however the local stresses on the polymer material should first beevaluated by the client.

Two Bolt Pipe Clamps
Two Bolt Pipe Clamps

How can I model your supports into CAESAR II?

Our spring hangers, constants, and variables arealready in Caesar II – Rigid supports can be modeled as stops or restraints inthe direction required.

How vital are pipe stess results to pipe support design?

Thisis a vital portion of the pipe support design. It provides us the loads that weneed to design the pipe supports.

Stress Analysis of a Variable Spring Support
Stress Analysis of a Variable Spring Support

If a constant spring always allows the pipe to move downwards, then how does upthrust work?

Springs allow the pipe to either move up ordown. An upthrust is our base-mounted constant wherein the load is above us andthe support is from below.

Upthrust Constant with Corrosion Resistant Coating
Upthrust Constant with Corrosion Resistant Coating

What should we do if we get more or less cold load than what is specified in the spring hanger?

If you have too much or too little load,artificially add or detract weight at the spring hanger location by means of a hoist.for example. Once the travel stop is removed you can then adjust to your new orcorrect cold load.

Are u-bolts allowed for insulated steam lines?

Yes, u-boltscan beused on insulated steam lines.

U-Bolt
U-Bolt Assembly

What are the things to be considered while de-blocking the spring hanger?

The major point to consider while de-blocking a spring hanger would be to makesure that you are at your true cold condition which means that you can applythe correct installed load that the spring is set to.

Variable Spring Set to Cold Load of 10,413 lb.
Variable Spring Set to Cold Load of 10,413 lb.

What are hot settings, piston setting, cold settings, and pre-set of a snubber?

Hot settings are the settings at the operatingconditions. Cold settings are the settings at the installed position orstart-up. The piston setting is the location of the position within the snubber at the cold position. Pre-set can refer to the setting specified by theengineer due to the anticipated movement.

Hydraulic Snubber Pre-set to the Midpoint of the Overall Stroke of 6'
Hydraulic Snubber Pre-set to the Midpoint of the Overall Stroke of 6″

How much compressive strength does the marinite material permit?

4000 PSI is the recommended strength for marinite material.

Marinite Slide Plate
Marinite Slide Plate

For offshore platform applications, do you recommend stainless steel base material for the sliding plate?

Yes. We do recommend stainless steel slide plates over thegalvanized material for it's longevity for the offshore application.

Stainless Steel
Stainless Steel Slide Plate

How can we use slide plates effectively for steam lines?

You would need to use the insulation type slideplate, ie: marinite, to insulate from the heat with PTFE on top of the structureto absorb the impact load if you have any steam hammers.

Slide Plate Assemblies with 2 3/4' Marinite Blocks
Slide Plate Assemblies with 2 3/4″ Marinite Blocks

What is the axial restraint between the foam insulation and a pipe clamp?

Axial restraint is usually the clamping forceand in case axial load is considerably higher, axial stops are welded to theinside of the clamp to prevent axial movement of the insulation within thesupport.

Cold Insulated Pipe Anchors with Axial Stops
Cold Insulated Pipe Anchors with Axial Stops

What is general curing time when referring to pre-insulated pipe supports?

Curing time for pre-insulated pipe supports is the time taken to mixpolyisocyanurates with polyol properly in order to achieve the desired density.

Cryogenic Pre-Insulated Pipe Supports
Cryogenic Pre-Insulated Pipe Supports

What is the purpose of the spring “lock” on a variable spring can?

The purpose of the spring “lock”mechanism is to provide the customer with a pre-loaded support and thehydro-testing of the line must be done with the locks in place to prevent fromdamaging the support.

How do we inspect load cells and what is the criteria for their positioning?

A load cell is only the measuring device forcalibration and it is used to test all our spring cans and constants.

If a mechanical snubber fails, can we have some locking arrangement to restrict complete imbalance and avoid major catastrophe?

We recommend that you put a sway strut in its place. That is a temporary fix until the snubber isreplaced.

Large Custom Sway Struts
Large Custom Sway Struts

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