PT&P Designed and Fabricated Variable Springs for a Refinery in Texas City

July 20, 2020

PT&P Designed and Fabricated Hanger and Base-Type Variable Springs, Constant Spring Supports, and Sway Struts for a Refinery in Texas City

Type: F-Type Variable Spring Support Assemblies
Design: Operating Loads from 3000 lb. to 4000 lb.
Movement of 1”
Material: Carbon Steel
Testing: Load & Travel Test |  Q.C. Inspection

Pictured here is a Type G variable spring hanger assembly designed for an operating load up to 4000 lb. and 1” movement. This type of support assembly is formed by welding two standard spring assemblies to the ends of a pair of channels. The Type G assembly is especially adaptable for avoiding interference in spaces where the headroom is limited. The assemblies are fabricated from carbon steel and underwent spring load tests before shipment.

PT&P Variable Spring Supports

January 10, 2017

Big Ton Spring Supports Designed for Propane Dehydrogenation Facility

June 27, 2016

Big Ton Spring Supports Designed for Propane De-Hydrogenation Facility

PT&P custom designed big ton spring supports for a propane dehydrogenation facility in Texas. The components within these assemblies include the spring housing, load columns, travel stops, spring coils and lifting lugs. While both assemblies measure 42” x 24” x 26-1/2”, they were each modified based on independent specifications for operating loads and movement. The first will accommodate a load of 94,261 lb. and 0.085” of movement, while the second will accommodate a load of 102,219 lb. with 0.08” of movement.

This type of support is ideal for applications, such as pressure vessels, that combine very heavy loads with thermal expansion because of the stability they provide. The big tons were tested in the load cell to insure proper operation throughout the entire working range of the coils.

What are the Variable Spring Types?

May 16, 2014

We offer seven different configurations for Variable Spring Supports (Type A, B, C, D, E, F, G). Click here for an in-depth explanation of each configuration.

Diagram of each Variable Support Type

What happens if variable spring variability increases?

February 11, 2011

When the variabilityof a variable springexceeds the MSS standard of 25%, the designer's first option would be to lowerthe spring rate so that the difference in load with the same amount of movementwould be smaller than that associated with the higher spring rate. The designerwould continue this exercise until a variability factor of less than 25% isachieved.

What is a spring support?

We refer to our spring supports as any assembly which includes a spring(either variable or constant) that can accommodate both a pipe load and a pipemovement.

U-Type Constant Springs Custom Designed for Large Travel for an Oil Refinery

Variable Springs Constant Springs

How do I set (load) a spring support?

November 2, 2010

In order to set (load) a spring support, you must ensure that the pipe system is at its cold (installed) state. (All hydro-testing has been completed.) At this point, with variable springs, the lower travel stops should be removed. Adjust the load at the load column of the spring so that a load slightly above the cold load is reached. The remaining travel stops can now be removed. Note: Excessive force should not be required to remove the travel stops at this time.

See Video on How to Remove Travel Stops from a Variable

See Video on How to Remove Travel Stops from a Variable.

What are the sizes of spring supports?

For variable springs there are 23 sizes with loads ranging from 50 lb. through 50,000 lb. For constant springs, there are 110 sizes with travel ranging from 1″ to 14″ and loads ranging from 0 lb. to 90,000 lb.

F-Type Variable Springs for a Local Chemical Plant

F-Type Variable Spring Supports

24,500 lb. Load PTP- 8 Type C Variable Spring Assemblies
PTP-8 Type C Variable Spring Assemblies

Figure 100 C-Type Constant Springs


PTP 100-C Size 84 Constant

How do you read the load indicator on a spring support?

To read the load indicator on a variable spring support, you need to read the measurement aligned with the bottom of the spring load indicator.

Load Indicator on a Variable Spring

How do you attach a spring support to a rod?

There are different ways to attach a spring support to a rod. For A-Type constants and variables, you need two separate rods. The top plate of the assembly includes a threaded piece that will connect to an upper rod. A second rod will be connected to the bottom by the spring's threaded load column. For B-Type and C-Type constants and variables, you need one rod to attach to the spring assembly's threaded load column. For D-Type and E-Type variables, a single rod runs from the bottom through the top of the spring and hex nuts are used to secure the rod in place. For D-Type and E-Type constants, a single rod is attached using a turnbuckle.

Variable Spring and Rod Assemblies
Variable Spring and Rod Assemblies

How much weight can a spring support?

The maximum load that a standard variable spring can support is 50,000 lbs. The maximum load that a standard constant spring can support is 90,000 lbs. A big ton spring support can be be used for loads greater than these standards.

Constant Spring Designed for a 35, 144 lb. Load
Constant Spring Designed for a 35, 144 lb. Load

How do I remove a spring support?

In order to remove a spring support, first you must ensure that the spring is at its designed cold (installed) position. Next, re-install the travel stop(s) in the support. Then, provide adequate temporary support for the piping system. Once you have adequate support, you can release the load from the spring. Finally, remove the spring support from the piping system.

Variable Spring Support with Travel Stops in Place
Variable Spring Support with Travel Stops in Place

How do I check the load setting of a spring support?

To check the load setting, examine the position of the bottom of the load indicator with respect to the scale on the spring's tag. Read from the bottom of the load indicator to determine position. Next, look at the size of the spring located on the tag. Then, refer to the appropriate load and travel table (Constant Load & Travel Table or Variable Load and Travel Table) to determine the respective spring rate and the “0” load (minimum working range load). Multiply the spring rate by the position value and add that to the “0” load value.

How do I inspect a spring support?

Use this 10-point operational integrity check list when inspecting spring supportsin the field:

  • Beam attachment
  • Beam attachment pin
  • Spring hanger attachment
  • Load flange movement
  • Spring coil corrosion
  • Check load indication for hot load
  • Note load deviations
  • Turnbuckle/locknuts
  • Threaded rod/weldless eye, hex nuts
  • Pipe clamp attachment pin
For more information, or assistance with accomplishing this check-list in the field, please see our field services page.
Corroded Variable Spring Support
Corroded Variable Spring Support

How can I size a variable spring support?

In order to size a variable spring support, you must know the cold load, the hot load, and the amount of travel of the pipe system. From that you can determine the required spring rate, and then review the variable spring support load and travel table to locate the correct size spring for your design.

Load and Travel Table

What is the maximum load variability of a variable spring hanger?

Per the MSS standards, the maximum recommended variability for a variable spring hanger is 25%. If required, you can specify a variability less than 25%.

Variable Spring and Cro-Moly 3-bolt Clamp Assemblies for a Power Generation Facility
Variable Spring and Cro-Moly 3-bolt Clamp

What is meant by “rod take-out” in spring supports?

The rod take out (RTO)is the amount of space between the upper attachment point and the lower attachment point of spring hanger assembly.

Rod-Take Out Indicated on a Variable Spring Hanger
Rod-Take Out Indicated on a Variable Spring Hanger

What does travel mean when discussing spring supports?

When dealing with variable spring supports, travel refers tothe amount of deflection from our installed position to our operating position.When dealing with constant springs, travel refers to the total amount ofdeflection, which could be accommodated by the support.

Spring Support Travel

What does the hot or cold setting mean on a variable spring support?

The “cold” setting of a variable spring support refers to the installed position and the associated load being carried by the support at that time. The “hot” setting refers to the operating position and subsequently the associated load being carried by the support at that time.

Cold Setting Indicated by the White Diamond on a Variable Spring Support
Cold Setting Indicated by the White Diamond on a Variable Spring Support

What are spring cans?

Spring can” is the general term used to describe either variable or constant spring supports.

Custom Spring Can with Slide Plates
Custom Spring Can with Slide Plates


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