Product

What Is a Pipe Nipple?

A pipe nipple is a short piece of pipe with external (male) threads on one or both ends. Its job is simple—join two female-threaded components—yet the design and execution matter a lot for sealing, pressure integrity, corrosion resistance, and maintenance. Thread forms may be NPT (tapered, common in North America) or BSP (BSPT/BSPP families, common outside North America).

1) Types of Pipe Nipples

Below are common types—plus when to use each.

  • Carbon nipple – General service water/air; economical. Typically made to ASTM A733/A106 or equivalent, in Sch. 40/80/160. ASTM International | ASTM+1
  • Galvanized nipple – Carbon steel with zinc coating for wet or mildly corrosive environments; verify hot-dip vs. electro-galv. (A733 explicitly covers zinc-coated). ASTM International | ASTM
  • Black pipe nipple – Uncoated carbon steel for indoor, dry service or where downstream coating will be applied. 麦克马斯特
  • Stainless nipple – Chloride-bearing or sanitary environments; choose 304/316 per media resistance. A733 also covers austenitic stainless nipples. ASTM International | ASTM
  • Welding nipple – Ends prepared for welding (e.g., bevel) on one side and threads on the other; useful for transitions.
  • Seamless pipe nipple – Preferred for higher pressure/temperature cyclic service; A733 covers both welded and seamless. ASTM International | ASTM
  • Reducer (unequal) nipple – Different thread sizes at each end; compact alternative to bushing + nipple.
  • Barrel nipple – Straight length with threads both ends and a plain section between.
  • Hex nipple – A wrenching hex in the middle for easy make-up/tear-down.
  • Close nipple / running nipple – Threads run nearly the whole length (no unthreaded land); great for extremely tight assemblies but hard to remove once installed. GTeek
  • Hose nipple – One barbed end for hose, one threaded end for the system.
  • Flange nipple – One end threaded, the other flanged (bolt-up) for quick disassembly.

New elements (beyond the usual list): manufacturing styles

  • Cut nipples – Threads are cut into tube/pipe; flexible for short runs and custom lengths.
  • Machine-from-solid – Turned from bar; tight concentricity and custom geometries (hex shoulders, special tapers).
  • Swaged/forged nipples – Ends formed for wall reinforcement; good fatigue behavior.

2) Supply Range for Pipe Nipples

Material

  • Carbon steel (e.g., A106, A53), stainless (304/316), and others on request (e.g., 321 for heat, 904L for chlorides). A733 defines carbon and austenitic stainless nipples. ASTM International | ASTM

Standards (by function)

Dimensions

  • NPS 1/8″–12″ typical; length from “close” up to long patterns (e.g., 12″+), with schedules Sch. 40/80/160 depending on rating. Reference tables in A733/EN 10241 and thread standards for exact thread engagement. ASTM International | ASTM+1

Finishes

  • Black (oiled), hot-dip galvanized, electro-galv, pickled & passivated (stainless), nickel-plated (select), PTFE-coated threads, and pre-applied sealant options (saves assembly time). 麦克马斯特

New elements: quality & testing options you can specify

  • 100% thread gauge verification (go/no-go) to ASME/ISO.
  • Hydrostatic test to specified bar/psi (or pneumatic with leak-snoop under safe protocols).
  • PMI (positive material ID) for alloy grades.
  • NDE on welded product: dye-penetrant on seam/ends, radiography on request.
  • Salt-spray hours for coated/galvanized surfaces per ASTM B117.

3) Pipe Nipple Applications

  • Plumbing/HVAC – Manifolds, meter sets, pump tie-ins (galvanized or black).
  • Industrial fluids – Oils, coolants, process water (carbon or stainless).
  • Compressed air & gases – Verify thread standard and sealant; avoid mixing BSP/NPT.
  • Fire protection – Black steel per project specs; watch for listed/approved requirements.
  • Food & pharma – 316L, cleanable designs, thread sealant compatibility.
  • Marine & offshore – Hot-dip galvanized or 316/316L; check pitting resistance.

(Note: “galvanized pipe nipple” is just a coating variant of carbon steel—same forms apply.) 麦克马斯特

4) Pipe Nipple Standards

  • ASTM A733 – Core product spec for welded/seamless nipples (carbon & austenitic stainless), in standard steel pipe sizes 1/8–12″; covers black and hot-dip galvanized. ASTM International | ASTM
  • Carbon Steel Pipe Nipple – Often manufactured from A53/A106 pipe to A733 nipple spec (verify MTRs). 麦克马斯特
  • Stainless Steel Pipe Nipple – Austenitic grades under A733; choose 316/316L for chlorides. ASTM International | ASTM
  • DIN 2982, BS EN 10241 – European scope for threaded steel fittings and common nipple patterns compatible with BSP threads. (EN 10241 replaced older national standards.) CNK Pipe Fitting+1

5) Dimension Standards

NPT Pipe Nipple Dimension Standard (ASME B1.20.1)

NPT uses a 1:16 taper for pressure-tight joints. Key parameters are threads-per-inch, hand-tight plane (E), and effective thread length (L2). Example: 3/4″ NPT has 14 TPI and ~1.050″ OD at the thread crest; reference tables for engagement/lengths. 统一合金+1

Selection notes (NPT):

  • Use joint compound or PTFE tape; don’t seal on the crest.
  • Target 2–3 turns past hand-tight for steel; back off for alignment only if rating allows.

BSP Pipe Nipple Dimension Standard

BSP comes in two families: ISO 7-1 (BSPT)—tapered male (R) sealing in tapered/cylindrical female (Rc/Rp) for pressure-tight joints—and ISO 228-1 (BSPP)—parallel threads (G) that need a gasket/O-ring at a face or captive seal. Dimensions align across ISO 7-1 and ISO 228-1 for diameter/pitch, but the sealing philosophy is different. 工程工具箱+2Swagelok Georgia+2

Avoid a common mistake: BSPP male will thread onto NPT female for a few turns and still leak—match thread standard, not just size.

6) Material Grades of Steel Pipe Nipples

Carbon Steel

  • Cost-effective, wide schedule range, weldable. Galvanize for wet service. Per A733, both welded and seamless are acceptable; pick seamless for higher fatigue or pulsation. ASTM International | ASTM

Stainless Steel (304/316)

  • Excellent corrosion resistance; 316/316L better in chlorides. Use pickling/passivation and avoid zinc-based sealants where media compatibility is critical. A733 includes austenitic nipples. ASTM International | ASTM

Practical Buying/Engineering Checklist (new)

  1. Thread system: NPT (ASME B1.20.1) or BSP (ISO 7-1 / ISO 228-1). Never mix. 统一合金+1
  2. Pressure/temperature: Choose schedule and seamless vs welded accordingly.
  3. Corrosion: Black vs hot-dip galvanized vs stainless; consider media and environment. ASTM International | ASTM
  4. Length style: Close, short, long; check wrenching features (hex). GTeek
  5. Finish & sealant: Pre-applied sealant can save assembly time; verify chemical compatibility. 麦克马斯特
  6. Compliance: Call out A733 or EN 10241/DIN 2982 as applicable, with MTRs. ASTM International | ASTM+2CNK Pipe Fitting+2
  7. QA: Request gauge checks, hydro test, PMI, coating salt-spray hours when critical.

Installation Tips (new, quick)

  • Inspect threads with a go/no-go gauge; reject galling or burred crests.
  • Apply PTFE tape or compound appropriate to the thread system (seal on threads for NPT/BSPT; seal on gasket/face for BSPP). Swagelok Georgia
  • Tighten with proper wrench flats (use hex nipples to avoid marring).
  • Pressure test and re-torque after thermal cycling if specified.

Sustainability & Lifecycle Notes (new)

  • Prefer stainless where life-cycle replacement of galvanized would be frequent.
  • Hot-dip galvanizing provides sacrificial protection; verify coating thickness where long life is needed. ASTM International | ASTM
  • SS TBE Pipe Nipple – Threaded both ends (BSPP or NPT).
  • Black TOE Pipe Nipple – Threaded one end for transition pieces.
  • Galvanized Seamless Pipe Nipple – Corrosion resistance plus seamless strength. 麦克马斯特
  • How To Install Pipe Nipple For Plumbing Piping? – Step-by-step with thread inspection, sealant selection, and torque guidance.
  • What Is a Pipe Coupling? – When a coupling + short pipe beats a reducer nipple (and vice versa).

Sources & Further Reading

  • ASTM A733 – Welded & seamless carbon and austenitic stainless steel pipe nipples; black and zinc-coated; sizes 1/8–12″. ASTM International | ASTM
  • EN 10241 – Steel threaded pipe fittings (BSP). CNK Pipe Fitting+1
  • DIN 2982 – Common reference for stainless double-ended nipples in EU catalogs. GTeek+1
  • ASME B1.20.1 – NPT thread dimensions and engagement. 统一合金
  • ISO 7-1 & ISO 228-1 – BSPT (taper) vs BSPP (parallel) threads and sealing differences. 工程工具箱+2Swagelok Georgia+2

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