Overview
ASTM B622-23 covers seamless pipe and tube in listed nickel and nickel-cobalt alloys, normally supplied solution annealed and descaled. Procurement must distinguish pipe from tube, select the exact UNS alloy, dimensions and condition, and define tension, hydrostatic or nondestructive electric testing plus B829 general requirements.
Designation and acceptance
B622 is a seamless tubular product specification for a defined alloy list; welded products use different specifications. Pipe and tube can share alloy chemistry but use different dimensional identities and end-use conventions. The solution-annealed/descaled condition, exact OD/NPS and wall, length, end preparation, test route and piping/equipment code must be written into the order rather than inferred from an alloy trade name.
Members and selection
| Designation | Selection context |
|---|---|
| Seamless pipe | Order by NPS/OD and wall or schedule basis accepted by the design, with ends and code requirements. |
| Seamless tube | Order by exact outside diameter and wall with tube tolerances, length and equipment-service tests. |
| Ni-Cr-Mo corrosion alloys | Select exact UNS from media, temperature, fabrication and code qualification. |
| Nickel-cobalt/high-temperature alloys | Confirm that the listed alloy, solution condition and design basis match the service. |
Comparison framework
| Criterion | Decision context |
|---|---|
| Pipe vs tube | Dimensional identity, tolerances and application conventions differ even within one seamless standard. |
| Seamless vs welded | B622 does not qualify welded pipe/tube; weld route and acceptance belong to separate documents. |
| Alloy vs product | UNS chemistry identifies alloy but not tubular dimensions, tests, condition or code acceptance. |
| Hydrostatic vs NDE | The permitted pressure or nondestructive electric test route must match the order and governing equipment specification. |
Performance
- Acceptance under ASTM B622 Nickel Pipe/Tube depends on the exact alloy or grade, delivered condition, product geometry and specified test basis rather than the standard number alone.
- Wall variation, surface contamination, unplanned cold work and heat tint can affect corrosion or pressure integrity.
- Service suitability remains an engineering decision: B622 material conformance does not establish system design, allowable stress, weld procedure, fittings compatibility or corrosion life.
Orderable product scope
- Seamless nickel-alloy pipe in NPS/OD and ordered wall for process piping.
- Seamless nickel-alloy tube in exact OD and wall for equipment or instrumentation duty.
- Cut or random lengths with specified ends, bore cleanliness and protective closure.
Processing
- Keep bore and surfaces free from iron, sulfur, chlorides, oil and shop contamination.
- Qualify welding, bending and heat treatment for the exact alloy, wall and code even though mill product is seamless.
- Control pickling/descaling and final cleaning so corrosion-resistant surfaces are not damaged.
Applications
- Chemical-process and pollution-control piping using a listed corrosion-resistant alloy.
- Heat-transfer, instrumentation or equipment tubing where B622 scope and dimensions fit.
- High-temperature or severe-media service only after piping/equipment-code and corrosion qualification.
Selection
- Confirm that ASTM B622 Nickel Pipe/Tube actually covers the required product form and manufacturing route before comparing grades or quotations.
- Select alloy or grade and delivered condition from service, fabrication, section size and required property evidence; do not infer condition from a trade name.
- Require a written technical comparison and responsible-engineer approval before substituting another standard, alloy, condition or product route.
Procurement
- State ASTM B622-23, exact UNS alloy, seamless pipe or tube and solution-annealed/descaled condition.
- State NPS/OD, schedule or nominal/minimum wall basis, length, quantity, tolerances and end preparation.
- Define tension, hydrostatic or NDE route, dimensional tests, surface/bore cleanliness and any supplementary examination.
- Invoke ASTM B829-24 and require inspection report, heat/lot traceability, capped ends and contamination-safe packing.