The externally pressurized expansion joints are 37.5″ in diameter and 36″ face-to-face. The bellows are 304 stainless steel, and the flange and ring are carbon steel. This expansion joint is rated for 232 psig with 5″ axial compression and temperatures up to 189°F. All bellows longitudinal welds were 100% x-rayed, all carbon steel welds were dye penetrant examined and each unit was hydro-tested to 348 psig. A total of 56 units were fabricated for a cooling system in a new university for women in the middle east.
Externally Pressurized Expansion Joints > Blog Articles
These externally pressurized expansion joints are 16″ in diameter and 60-1/4″ face-to-face. The bellows are fabricated from 304 stainless steel, and the rest of the expansion joint is fabricated from carbon steel. They are custom designed for 8″ axial movement and 150 psig at 176°F, with a spring rate of 2,152 lb./in. Each expansion joint was hydro-tested, radiographic tested, and dye penetrant tested prior to shipment.
Pressure relief safety valves are designed to control steam pressure. This prevents over pressurization, which can result in serious accidents and costly damage to equipment. When the relief valve operates, there is a steam flow. During venting of the pressure, the steam is discharged to the atmosphere using an open system that could cause blow-back. The safe answer to open venting is a closed sealed venting system. The closed system eliminates steam blow-back and hazard conditions for the employees. The closed venting system uses a bellows type safety valve connector.
These 15 pressure relief safety valve connector expansion joints were manufactured from 316SS, A-335 P22, A-387 Gr22, A106, and A-516-70. They were externally pressurized to prevent steam blow back, and will be attached to the relief valves in a power plant. The expansion joints will assist in maintaining pressure as well as provide for 7″ axial and 6″ lateral travel. They can handle applicable loads of up to 150 PSIG at 535°F and 460 PSIG at 885°F, but can function if temperatures reach 1,000°F. They range from 30″ to 85″ in length and weigh between 400 lb. and 1,600 lb. Dye penetrate, air, and soap bubble tests were completed for quality and performance assurance.
Single Tied Expansion Joints for a Pipeline in Alaska
The expansion joint assemblies are fabricated entirely from stainless steel with a design pressure of 50 PSIG. They are designed with tie rods that do not permit axial movement, but allow for lateral movement up to 1/2″. The expansion joints will be used on a process line that contains exhaust gas and hydrocarbon vapor at a low concentration. It will connect an oil tank with a vapor control system.
The expansion joint assemblies are fabricated for a 12″ pipe and are designed for 2-1/2″ lateral movement. The design pressure is 276 PSIG with a design temperature of 626°F. 316L stainless steel was used for the bellows and tie rods. The expansion joints include 300 lb. raised face stainless steel flanges to accommodate low spring rate requirements.
Hinged Expansion Joints with Refractory Lining
Hinges cause the unit to bend in a single plane. The hinge mechanism is designed to accept the full pressure thrust.
- Design Pressure: 75.4 PSIG
- Design Temperature: 1400°F
- 100% X-ray Tested
- Pneumatically Tested weld seams to 83 PSIG
Elbow Pressure Balanced Expansion Joints
The expansion joints are fabricated for a 36″ pipe and are designed with Inconel® 625 grade LCF bellows. They include a liner provided with drain holes to prevent accumulation of corrosive condensation.
Inline Pressure Balanced Expansion Joints
- Design: 125 PSIG, Temperature: 244°F
- 304 SS Bellows, Flanges & Liners
- Designed to Balance 48,000 lb. of Pressure Thrust
Externally Pressurized Expansion Joints
These expansion joints are fabricated for a piping system in a steam plant. They include 304 SS bellows and carbon steel shell and flanges, and are designed for 150 PSIG and 350°F.
These expansion joints are designed for a 55″ diameter overhead vapor line at a refinery. The overall length is 310″ and the bellows are fabricated from 625 LCF. The expansion joint is designed for 50 PSIG and 1075°F.
Externally pressurized expansion joints are suited for piping systems that require large amounts of axial compression or extension. In externally pressurized expansion joints, the bellows elements are arranged so that the media flow is on the external surface of the bellows. Externally pressurizing the bellows eliminates pressure instability as a limitation to the design and permits the absorption of large amounts of axial expansion.
Typical movement conditions that occur in a piping system:
- Installation: allow one cycle for installation misalignment
- Start-up / Shut down: movements produced between the minimum ambient temperature and the maximum start-up temperature. This is normally a very low number of cycles.
- Operating: movements produced due to temperature fluctuations during system operation. This is typically a very small movement for a very large number of cycles.
- Excursion: movement resulting from a worst case / upset scenario, occurring during system operation. This is normally a very low number of cycles.
U.S. Bellows externally pressurized expansion joints are designed for 1000 cycles for any one tabulated movement shown. Movement may be increased, decreasing the cycle life, by using the graph below. This graph may also be used for superimposing more than one movement condition on the bellows at one time.
Using the graph: example: 2500 cycles reads C.F. of 1.23
- Enter the graph horizontally at the number of anticipated cycles or the movement condition being considered
- Move vertically until the graph I intercepted
- Move horizontally and read conversion factor
Fourteen Externally Pressurized Expansion Joints Designed for NASA
- 4″ to 14″ diameter range
- 21″ to 42″ O.A.L. range
- 304 stainless steel bellows
- 300 lb. carbon steel flanges
- Design conditions: 200 PSIG at 500ºF
- Internal guide rings serve as limit stops
- 100% dye-penetrant examined
- Hydrostatically tested
Externally Pressurized Expansion Joints for a Steam Plant in Kent, Ohio
- 10″ to 24″ diameter range
- 304 stainless steel bellows
- Carbon steel shell and flanges
- Design conditions: 150 PSIG at 350ºF
- Maximum of 4″ compression
- Hydrostatically tested
These externally pressurized expansion joints were designed in various sizes for NASA. The diameter ranges from 4″ to 10″ and the overall length ranges from 21″ to 42″. The expansion joint assemblies were fabricated with 304 stainless steel bellows and 300 lb. carbon steel flanges. The design conditions were 200 PSIG at 500ºF. Externally pressurized joints are unique in that they can absorb large amounts of axial travel.
They also incorporate internal guide rings that serve as limit stops in case of anchor failure. The expansion joints were 100% dye-penetrant examined and hydro-tested prior to shipment.
These 15 pressure relief safety valve connector expansion joints were manufactured from 316SS, A-335 P22, A-387 Gr22, A106, and A-51670. They were externally pressurized to prevent steam blow back. These externally pressurized expansion joints were attached to the relief valves in the power plant. They assist in maintaining pressure as well as provide for 7 axial and 6 lateral travel. These joints can handle applicable loads of up to 150 PSIG at 535F and 460 PSIG at 885F, but can function if temperatures reach 1,000F. They range from 30 to 85 in length and weigh between 400 lbs and 1,600 lbs. Dye penetrate, air, and soap bubble tests were completed for quality and performance assurance.
U.S. Bellows/PT&P specially designed and fabricated 40 externally pressurized expansion joints for the piping system of a steam plant in Kent, Ohio. The sizes of the expansion joints ranged from 10 to 24. The expansion joints were designed at 150 psig and 350oF for maximum of 4 compression, and fabricated with 304 SS bellows and carbon steel shell and flanges. The joints were leak tested before shipment.
These expansion joints were designed for 13″ movement. They are capable of withstanding temperatures of 1100F. These particular joints are externally pressurized. Externally pressurizing a bellows eliminates squirm as a limitation to the design and permits the safe acceptance of large amounts of axial thermal expansion.