DN65 (2½") metal expansion bellows — axial movement, EJMA build, UK stock
What the UKGP-MEB-02 DN65 (2½") metal expansion bellows does
The UKGP-MEB-02 is a DN65 (2½") multi-ply 321 stainless steel metal expansion bellows (also called a metallic expansion joint or stainless bellows compensator) built to EJMA Section 4. It absorbs axial thermal growth in high-temperature steam, hot oil, flue-gas and process pipework where elastomer rubber bellows cannot survive the operating temperature. The bellows convolutions deform elastically to accept up to 40 mm of axial movement plus 8 mm of lateral offset, allowing rigid steel pipework to grow and contract without transmitting axial load into pumps, vessels and connected equipment.
Why specify a metal expansion bellows for steam, hot oil and exhaust
Above roughly 110 °C an EPDM rubber bellows is out of spec — the elastomer hardens, the bond to the flange ring fails, and the joint leaks. A stainless steel metal expansion bellows like the UKGP-MEB-02 works to 550 °C continuously and 800 °C peak in the 321 grade, making it the only realistic choice for LP/MP/HP steam mains, hot-oil thermal-fluid loops, flue-gas ducting, dryer manifolds and turbine bleed lines. The single-ply equivalents you see in low-cost imports cycle-fatigue in months on real-world steam duty; multi-ply construction puts three thinner plies in parallel so each ply takes less strain per cycle, which is what delivers the 20+ year service life the EJMA standard targets.
Movement capacity, anchors and tie-rod restraint
The UKGP-MEB-02 DN65 (2½") metal expansion bellows is an axial joint — it must be installed between two anchored points so the pipework forces the bellows to compress and extend rather than letting line pressure pull it apart. Pressure thrust on a DN100 bellows at 16 barg is around 13 kN; without main anchors, that load tears the convolutions off the tangent. Where main anchors aren't feasible, specify the tied-lateral or universal variant instead, or order the UKGP-MEB-02 with our factory-fitted tie-bar restraint kit. Always size at no more than 75 % of rated movement to leave headroom for installation tolerance and over-temperature events.
Metal vs rubber expansion bellows — when to pick which
Rubber bellows are quieter, cheaper and unbeatable for pump-vibration isolation on water systems below 100 °C. Metal expansion bellows are the right call above 110 °C, for steam, hot oil, flue-gas and chemical service, and wherever ozone, UV or hydrocarbon exposure rules out elastomers. For a side-by-side comparison see our rubber vs metal expansion joints guide linked below.
Standards: EJMA, PED and CE marking
Every UKGP metal expansion bellows is built to the Expansion Joint Manufacturers' Association (EJMA) Section 4 design rules, hydrostatically tested at 1.5 × design pressure and supplied with a signed certificate of conformity. Bellows above DN50 / above 0.5 barg fall under PED 2014/68/EU and are CE marked. Material certificates (EN 10204 3.1) on the 321 / 316L plies are available as a no-cost option — specify at order.
Price, lead time and ordering the UKGP-MEB-02
The UKGP-MEB-02 DN65 (2½") metal expansion bellows is £345 ex VAT, in UK stock for same-day dispatch on orders placed before 3 pm Mon–Fri. Specials — Inconel 625, PN25/PN40, weld-end terminations, hinged or universal arrangements — are quoted inside one working day.