Externally Pressurized Expansion Joints

Description

MULTI-PLY SAFETY FACTORS-

In a critical application, a multi-ply expansion joint can, in most cases, preclude a catastrophic failure. If a failure occurs in one ply due to corrosion or fatigue, the intact plies will work as a protective barrier to contain the pressure and the medium until a replacement can be made. Flex-Weld multi-ply expansion joints are designed to provide utmost safety in the event of system failure. The burst pressures are a multiple of the operating pressure making the Flex-Weld multi-ply bellows the most reliable component in the system.

CYCLE LIFE OPTIMIZATION-

The technical advantage of using multiple plies of thin wall thickness material is that less residual stresses are introduced at the time the bellows were formed. Overall, Flex-Weld multi-ply expansion joints have lower built-in and induced stresses which ultimately results in longer cycle life. Also, the thinner gauge multiple plies have less localized induced stresses during operation compared to a single thicker ply. The configuration of the convolutions (pitch, depth, contour, number of plies, ply thickness) of FLEX-WELD multi-ply expansion joints are optimized to offer the highest fatigue life.

COMPACT DESIGN-

Multi-ply expansion joints have more flexibility than conventional single-ply expansion joints and thus require less live length to accommodate a given movement. The live length of the bellows can be minimized to absorb a given combination of axial, lateral and angular movements. This results in an economical, compact assembly which can be installed in a minimal amount of space. An additional benefit is a small effective area, resulting in lower thrust pressures on the anchors and mechanical equipment in the system. LOWER THRUST FORCES – The multi-ply design results in lower spring rates. Also, the effective cross-sectional area of multi-ply expansion joints is less, compared to single-ply bellows, to accommodate a given movement. These two reductions result in lower forces and moments on the anchors, equipment and guides. A side benefit is that fewer anchors and guides will be required in the overall bellows piping system.

Externally-Pressurized Expansion Joints are Designed to Replace:

High-Maintenance Packed Joints
Space-Confining Pipe Loops
Costly Equalizing Expansion Joints

Submittals

Submittals Single Bellows Externally-Pressurized Expansion Joints (4” – 8” Axial Movement)
	4 inch	6 inch	8 inch
Pipe Weld Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi
Raised Face Flange Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi
Grooved Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi
Submittals Dual Bellows Externally-Pressurized Expansion Joints (8” – 16” Axial Movement)
	8 inch	12 inch	16 inch
Pipe Weld Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi
Raised Face Flange Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi
Grooved Ends	150 psi	150 psi	150 psi
	300 psi	300 psi	300 psi