Piping and Connection Technology
Fittings and Unions
Fittings and unions form the fixed but demountable joint between pipe, hose and equipment. With 9,331 references this is the largest group in the branch, and selection always comes down to four questions: which body shape joins the two ends, straight, elbow, tee, wye, bulkhead or reducer? Which sealing principle carries the joint, a compression ring on the pipe, a tapered R or NPT thread, or a parallel G or Rp thread with a separate seal? Which material suits the medium? And which pipe size and thread size are fixed on either side?
In the water-glycol loop of a data centre the material is the first exclusion criterion. Stainless 1.4571 and 1.4408 as well as PVC-U and PVDF can be used without restriction, brass and nickel-plated brass only in a loop that stays single-metal. Body shape and thread come second: pipe unions in 10 L, 12 L and 16 S, threads from M10x1 and M12x1.25 through G 1/8 to G 1/2 and Rp 1/4, plus NPT versions for imported assemblies.
- 7,216 items
- 7 manufacturers
- Net prices plus VAT
Buying guide
How to choose Fittings and Unions
What matters when choosing: properties, comparison and typical applications.
Selection in four steps
Selection criteria in detail
Body shape, sealing principle, material and size
| Criterion | Options in stock | Selection note |
|---|---|---|
| Body shape | straight, 90° elbow, tee, wye, bulkhead union, reducer, thread extension, union nut | bulkhead types for cabinet and enclosure pass-throughs, reducers only where the cross section allows |
| Sealing principle | compression and cutting ring on the pipe, tapered R and NPT thread, parallel G and Rp thread with a seal | tapered threads seal in the thread itself, parallel threads need a flat seal or O-ring |
| Material | stainless 1.4571 and 1.4408, brass, nickel-plated brass, PVC-U, PVDF | stainless and plastics unrestricted, copper alloys only in a single-metal loop |
| Pipe size | 10 L, 12 L and 16 S plus further sizes of the light and heavy series | L for the normal case, S where mechanical load is higher |
| Thread size | M10x1, M12x1.25, M22x1.5, G 1/8 to G 1/2, Rp 1/4, NPT 1/4" | check both sides separately and adapt rather than recut a thread |
| Hose side | male hose tail LW 9 and LW 13, 90° elbow hose tail, wye hose connector | hose tails need a clamp matched to the hose outside diameter |
Typical applications
- Connecting pumps, filters, heat exchangers and valves to the secondary pipework
- Transition from drawn stainless tube to equipment threads at the coolant distribution unit
- Bulkhead pass-throughs in cabinet and rack panels
- Adapting metric assemblies to the G and NPT ports of imported equipment
- Measuring and tapping points for pressure and temperature transmitters
- Repair and modification of existing loops without welding