Bellows — The Expansion Joints Blog

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Do you have a plant turnaround coming up?

October 24th, 2011 Comments off

Do you have a plant turnaround scheduled or planning one in the near future? PT&P is prepared to be there for you throughout the entire process. From planning, to execution, and follow-up, we have what it takes to accomplish a successful plant turnaround.

Prior to Your Turnaround:
- Call our field service team to assist with plant walk-downs to assess your plant for maintenance, repair or replacement of pipe supports and expansion joints
- Contact our quotations department for immediate pricing on pipe supports, expansion joints, or auxiliary steel needed during the turnaround.
- Consult our experienced engineers for guidance on support placement, materials, finishes, etc. to ensure optimum life of the supports.

During Your Turnaround:
- Use our field service team to guide you through installation, start-up, and replacement to safely and efficiently handle your turnaround.
- For quick delivery, PT&P stocks over 1500 bellows, over 100,000 lb. of insulation materials, over 30,000 spring coils, and over 1 million pounds of standard items

Post Turnaround:
- Receive training to monitor the supports, and identify potential failure, in order to prevent unplanned turnarounds in the future.
- Learn correct size and selection of pipe supports and expansion joints per application for any post-turnaround resolutions.
- Call on our field service team to develop a data book of existing pipe supports and expansion joints and their conditions in order to identify potential maintenance issues in upcoming turnarounds.

Examples:

Metallic Expansion Joint Refurbished in 2 Days

Metallic Expansion Joint Refurbished in 2 Days

A rectangular metal expansion joint was refurbished  on an emergency   basis for a local chemical plant. Upon arrival, it was acid washed and   dye-penetrant examined for any cracks.  View the full Article.

Refurbishment of 54" Pressure Balanced Elbow Turbine Crossover Expansion Joints

Refurbishment of 54" Pressure Balanced Elbow Turbine Crossover Expansion Joints

U.S.   Bellows, Inc. refurbished two pressure balanced elbow expansion joints with a quick turnaround for a power generation plant during outages.   They are designed for high pressure turbine crossover piping. The first 54″ outside diameter expansion joint leaked from a crack in the bellows   causing an unscheduled outage.  View the full article.

4" Single Expansion Joint

4" Single Expansion Joint

This expansion joint was received in the morning and shipped to the customer the very same day. The bellows, liner and cover were replaced and the carbon steel parts were sand blasted, cleaned and painted. A dye-penetrant test and hydro-test to 518 PSIG were performed prior to shipment. View the full article.

Same Day Turnaround Service on an 8" Single Expansion Joint

Same Day Turnaround Service on an 8" Single Expansion Joint

This expansion joint was received in the morning, refurbished by adding new bellows and limit rods, and then shipped the very same day. New 321 stainless steel bellows were fabricated and the existing flanges were reused by sandblasting and then painting for corrosion protection. View the full article.

New 2011 Expansion Joint Catalog

September 26th, 2011 Comments off

New 2011 Expansion Joint Catalog
To get your copy, fill out the request form. A number of improvements have been implemented based on valuable feedback from our customers and engineers.

- all new photographs
- a brand new section on past projects
- more expansion joint data tables

You can now download the expansion joint data tables from our online catalog.

Expansion Joint Burst Testing to Determine Ultimate Pressure Resistance

August 29th, 2011 Comments off

This week’s featured article is on expansion joint burst testing. The objective of a burst test is to determine the ultimate pressure resistance that a bellows can absorb prior to failure. Burst tests help determine the margin of safety and safety factor to be used in a specialized bellows design. During a burst test, hydrostatic pressure is slowly increased until failure occurs, which usually happens in one to two hours. Burst testing is conducted at ambient temperatures to determine a bellows pressure rating. We follow all the necessary safety precautions for personnel involved, such as placing the bellows in a high strength steel cage and using a safety shut-off switch. Based on the burst test results, a safety factor is applied, thus establishing the ultimate pressure rating.

Expansion Joint Burst Testing to Determine Ultimate Pressure Resistance Expansion Joint Burst Testing to Determine Ultimate Pressure Resistance

 

Fatigue Testing to Calculate a Life Span of 30,000 Cycles

August 16th, 2011 Comments off

Fatigue Testing to Calculate a Life Span of 30,000 Cycles

The video shows an expansion joint bellows being cycle tested through a specified design movement of 1-1/4″ to verify the calculated life span of 30,000 cycles. The number of completed cycles is recorded throughout the duration of the test. U.S. Bellows routinely performs this test to confirm designs and ensure a high quality product. We do extensive expansion joint product testing such as x-ray, burst, hydrostatic, ultrasonic, radiography, fatigue, PMI, pneumatic, magnet particle and helium leak testing depending on customer specifications. Each bellows and expansion joint unit goes through in-process quality control using a system of travelers, and a final in-house dimensional inspection is performed prior to shipping.

Understanding Bellows Squirm

April 19th, 2011 Comments off

All bellows have a critical pressure at which they become unstable. Instability can occur in either of two modes, column instability (or squirm), or in-plane deformation of the convolution side wall. Squirm affects the bellows as a whole, while in-plane deformation only affects one or more convolutes individually.

Bellows Squirm DrawingColumn Instability Column instability (or squirm), is the phenomena whereby the centerline of a straight bellows develops a sideways or lateral bow. This condition is most associated with bellows which have a relatively large length-to-diameter ration and is analogous to the buckling of a column under compressive load.
Bellows Squirm Drawing from EJMA

In-Plane Squirm
In-plane squirm is defined as a shift or rotation of the plane of one or more convolutions such that the plane of these convolutions is no longer perpendicular to the axis of an unreinforced bellows. It is characterized by tilting or warping of one or more convolutions. This condition is predominantly associated with high meridional bending stress and the formation of plastic hinges at the root and crest of the convolutions. It is most common in bellows which have relatively small length-to-diameter ratio.

Example of Bellows Squirm

How to Avoid Instability (or Squirm)
The test pressure should be less than or equal to 1.5 times the design pressure based on column or in-plane stability at ambient temperature material properties.

Categories: Bellows Tags:

Bellows Deflections

January 18th, 2011 Comments off

In order to properly specify expansion joints for piping systems, the piping specialist and must be aware of the various types of deflections that can be taken by an expansion joint bellows. Piping flexibility programs can determine where stresses are excessive, and if an expansion joint is necessary or not. Expansion joint placement and proper selection still depends on understanding the different types of bellows deflections.

Axial Deflection (View Axial Movements)

Axial deflection refers to movement of the bellows along the longitudinal axis of the bellows. Compression is the axial deflection which will shorten the bellows length, while extension is the axial deflection which extends the expansion joint. Often confusion occurs because thermal expansion in the piping will cause the expansion joint to compress. The specification for an expansion joint should always state the movements as they affect the expansion joint, and not as they are produced by the system. Piping which is operating at temperatures lower than ambient, such as in cryogenic systems, will contract, causing the expansion joint to extend.

Axial Deflection Read more…

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Two-ply Testable Bellows

November 29th, 2010 Comments off

U.S. Bellows designs two-ply bellows with 100% redundancy; therefore, if a leak occurs in the inner ply, the outer ply is designed for the full pressure and temperature. This design allows for the critical piping system to continue operating while plans for replacement can be formulated. This can prevent unexpected shut-downs saving valuable time and money.

Two-ply bellows also make it possible to pressure test and inspect for leaks during field inspections and in some cases if conditions permit, the expansion joint can be tested while in service. Universal, hinged and gimbal are some of the common types of expansion joints that include two-ply bellows. Sometimes a wire mesh is used between the bellows to ensure flow equalization between the plies of the bellows.

Most expansion joints in oil refineries, especially FCC units use two-ply bellows, but they are also ideal for regenerated catalyst standpipe, spent catalyst standpipe, recirculation cooled catalyst flue gas piping and hot gas expanded piping. Contact our team to have your single bellows expansion joint refurbished to include two-ply bellows.

44" Hinged Expansion Joint with Refractory-lining  and Two-ply Bellows

44″ Hinged Expansion Joint with Refractory-lining  and Two-ply Bellows

- Designed with two-ply Inconel® 625 LCF bellows, 5″ thick refractory-lining and 2″ thick attachment rings for part of a reactor piping system in a synfuels plant
- Pneumatically tested between the bellows plies and the complete expansion joint
- Thermal and structural Finite Element Analysis (FEA) was performed for the bellows operating temperature

- Designed with two-ply Inconel® 625 LCF bellows, 5″ thick refractory-lining and 2″ thick attachment rings for part of a reactor piping system in a synfuels plant- Pneumatically tested between the bellows plies and the complete expansion joint- Thermal and structural Finite Element Analysis (FEA) was performed for the bellows operating temperature

55" Refractory-lined Universal Gimbal Expansion Joint  with Two-ply Bellows55″ Refractory-lined Universal Gimbal Expansion Joint  with Two-ply Bellows

- Designed for a spent catalyst standpipe in a FCC unit & includes slotted hinges

- 163″ O.A.L and 60 PSIG at 1020°F, A516 GR 70 pipe and two Inconel® 625 LCF two-ply bellows

- 100% dye penetrant tested, 100% x-ray tested, pressure tested, pneumatic and vacuum tested between the bellows plies and the complete expansion joint

44" Universal Expansion Joint with Refractory-lining  and Two-ply Bellows44″ Universal Expansion Joint with Refractory-lining  and Two-ply Bellows

- Designed for a chemical plant in Venezuela

- 44″ diameter and 100 PSIG at 1000°F

- 321 SS two-ply testable bellows, A-387 GR 11 weld ends, 5″ vibra cast and 1″ abrasion resistant refractory

- Pneumatically tested between the bellows plies and the complete expansion joint

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