Piping components · Movements, pressure thrust, anchors and guides
An expansion joint lets a pipe or duct grow and move without overstressing it, but an untied bellows does not hold pressure on its own: the pressure thrust must go into anchors, and guides must keep the pipe straight. Specify the movements, the pressure and the anchoring together.
Metal bellows, rubber, PTFE and fabric expansion joints for pipelines and ducts, including tied, hinged and gimbal designs. Bridge and building expansion joints and floor profiles are outside this page.
CNFX editorial research · Sources checked October 11, 2026 · 6 sources
Calculate the pressure thrust the anchors must carry
US Bellows explains that internal pressure in a bellows is not balanced by pipe tension, so it must be resisted externally by main anchors. Tests show the bellows' mean (pitch) diameter predicts the pressure thrust very accurately; basing it on the corrugation sidewall annulus area is what US Bellows calls "the most serious misconception since it can lead to gross under prediction" of the load, using the inside diameter ignores the sidewall load and under-designs anchors, and using the outside diameter overstates it. [1][2]
US Bellows gives the effective area as the inside-diameter area plus a sidewall area, approximated with the mean diameter (ID plus corrugation height); in a comparison on 5 sample problems it reports that "the percent error involved in using the mean diameter approximation is generally less than 1% and only 1 1/2% in the extreme example". [2]
Editorial calculation: a bellows with a 300 mm mean diameter at 1.0 MPa (10 bar) has an effective area of about 0.0707 m², so the pressure thrust is about 71 kN. The main anchors must take that plus the bellows spring force; check the thrust at the highest pressure the line will see, including any pressure test.
Give the supplier the pipe or duct size, medium, design and test pressure and temperature, the axial, lateral and angular movements with cycles, and the anchor and guide layout.
02
Place main anchors, intermediate anchors and guides
US Bellows advises no more than one bellows between any two anchors; where more are needed, divide the line with intermediate anchors. Intermediate anchors do not carry the pressure thrust, but must take bellows deflection forces and friction from supports and guides. [3]
Guides direct movement into the bellows, stabilise its ends against squirm, prevent the pipe buckling under the pressurised column effect and support weight; compression systems with external main anchors need full lateral restraint guides. The full bellows thrust area sets the buckling pressure. [3]
Ask the supplier whether an untied, tied, hinged or gimbal design suits your layout, and for the loads each puts on your anchors and guides.
03
Choose metal, rubber, PTFE or fabric
Tongyong, Shunying and Allto between them list metal bellows compensators and expansion joints, rubber single- and double-sphere joints, PTFE-lined and hand-wrapped rubber joints, and duct expansion joints for boiler flue gas. [4][5][6]
Tongyong lists metal and non-metallic compensators; Hongyuan lists metal hoses, bellows and compensators; EagleBurgmann lists expansion joints with mechanical seals and gaskets; Shunying lists single- and double-sphere rubber joints and joints with tie rods; Allto lists anti-static and hand-wrapped rubber joints and metal hoses; Yuanda lists boiler flue-duct expansion joints; Hebei Leading lists rubber expansion joints with pipe and fittings. Ask each for rated movements, pressure and temperature for the exact joint. [4][5][6]
04
Bellows, ends, liner, restraint hardware, anchors and guides
Anchors and guides belong to the piping, not the joint, but are listed because the bellows cannot hold its pressure thrust without them.
Size, pressure, movements and spring rate for the quotation
Movements and pressures come from your pipe stress or duct layout. US Bellows supplies the relationships in the middle column; it gives no product ratings for your joint.
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Line: [pipe or duct size; medium; design and test pressure; temperature]
Movements: [axial, lateral, angular; cycles; vibration]
Layout: [isometric with anchors and guides; space between anchors]
Type: [untied bellows, tied, hinged, gimbal; rubber, PTFE or fabric]
Materials: [bellows, liner, flanges]
Documents: [effective area and spring rates; anchor load calculation; pressure test report]
12 companies list this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
Botou Tongyong Bellows Manufacturing Co., Ltd.
Manufacturing site to be confirmed for the order
Lists metal and non-metallic compensators, expansion joints and metal hoses.
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
How do I calculate expansion joint pressure thrust?
Multiply pressure by the bellows' effective area based on its mean diameter; US Bellows warns that using the annulus or inside diameter under-predicts the load. [1][2]
Do intermediate anchors carry pressure thrust?
No; they take bellows deflection and friction forces, while main anchors take the pressure thrust. [3]
Why do expansion joints need guides?
To direct movement into the bellows, prevent squirm and pipe buckling, and support weight. [3]
Sources and what still needs a direct check
Sources checked 2026-10-11. US Bellows is an expansion joint manufacturer; its technical bulletins explain pressure thrust, anchors and guides. EJMA standards were not read for this page. Supplier pages describe their own offers.
