FlowMarket
Where to source pipes, fittings and flanges: FlowMarket is a B2B sourcing network powered by an AI agent. You describe the pipework — material and grade, nominal size and wall thickness, pressure and temperature, the standard the parts must follow, connection type and any material certification — and the AI agent matches you with verified suppliers and stockholders, then requests prices and lead times from every match at once. Getting matched is free for buyers.
Sourcing pipes, fittings and flanges
Pipework is a commodity right up until the moment a standard is mismatched, and then it is scrap. Everything here is governed by norms — dimensions, pressure ratings, materials, flange drilling — and the norms from different regions do not interchange, however similar the numbers look.
So the most important thing to state is not the size but the standard. "DN100 PN16 to EN 1092-1" is a specification a supplier can fill exactly; "4 inch flange" is an invitation to send you something that will not bolt up.
What you can source
Pipe
Seamless or welded, in carbon steel grades such as P235GH and P265GH, stainless 1.4301/304 and 1.4404/316L, duplex for chlorides, and plastics — PVC, PP, PE and PVDF — for chemical and water duties. Sized by DN with a wall thickness schedule (SCH 10, 40, 80) or by outside diameter and wall in millimetres. Length, surface finish and whether the interior is pickled or passivated all matter for process work.
Fittings
Elbows, tees, reducers, caps and stub ends, in butt-weld, socket-weld, threaded, grooved or press-fit form. Butt-weld fittings match the pipe schedule and give a full-bore, permanent joint; press-fit systems are far faster to install and dominate building services; threaded and grooved sit in between. The joining method usually decides the fitting family before anything else does.
Flanges and joints
- Weld neck — the strongest and the default for pressure and cyclic duty.
- Slip-on & plate — cheaper and more forgiving on alignment, for lower-pressure lines.
- Blind — closes off a line or a vessel nozzle.
- Loose & lap joint — lets a lined or expensive alloy pipe use a cheap carbon steel backing flange.
What to specify when sourcing
These details decide both the part number and the price:
- Standard — EN, DIN, ASME/ANSI or ISO; state it explicitly, for every item.
- Material & grade — 1.4404/316L, P235GH, PE100, PVDF, and the delivery condition.
- Dimensions — DN or NPS with schedule, or outside diameter × wall thickness in mm.
- Pressure & temperature — design pressure and operating temperature, which set the rating.
- Media — what it carries; this drives material and any lining.
- Connection type — butt-weld, socket-weld, threaded, flanged, grooved, press or clamp.
- Flange detail — type, PN or class, and facing (flat, raised face, tongue and groove).
- Certification — EN 10204 2.2, 3.1 or 3.2, PED category, drinking-water or food approval.
- Surface & finish — galvanised, painted, pickled and passivated, or bright annealed.
- Quantities & lengths — metres or pieces per item, and whether cut lengths are needed.
EN and ASME do not interchange — check the bolt circle
The most expensive mistake in pipework sourcing is assuming a flange is a flange. A DN100 PN16 flange to EN 1092-1 and a 4-inch class 150 flange to ASME B16.5 are close in outside diameter and pressure rating, and they will not bolt together: the bolt circles, bolt counts and hole diameters differ. The same applies to pipe — DN and NPS are not the same series, and a nominal size does not fix the wall thickness without a schedule. Mixed standards on one site are common after a rebuild or an import, so say which standard the existing pipework follows as well as which you want supplied. The other detail worth naming early is the material certificate. For pressure equipment under PED, an EN 10204 3.1 certificate with the heat number is normally required, and it must be ordered with the material — sourcing it afterwards for stock already delivered ranges from expensive to impossible.