B31 piping codes
Choose the code for the piping service, such as B31.3 for process piping or B31.1 for power piping.
Technical guide
ASME Stainless Steel Standards
ASME requirements are selected by equipment and jurisdiction. A design code, component standard, dimensional standard and adopted material specification serve different roles and usually must be used together.
Pipe dimensionsASME B36.19-2022
Process pipingASME B31.3
Pressure materialsASME BPVC Section II
Decision summary
Build the standard stack from the governing code outward
A purchase line that says only “ASME stainless” is incomplete. Start with the applicable construction code, then identify component, material, fabrication, examination and documentation requirements.
BPVC construction rules
Pressure vessels and boilers use the applicable BPVC construction section plus referenced material and welding sections.
Section II materials
BPVC Section II reproduces adopted SA/SB/SFA specifications and provides code properties; it does not replace the construction code.
B36.19 dimensions
Standardizes dimensions for welded and seamless wrought stainless steel pipe.
B16 components
Covers flanges, fittings, valves and related pressure components within each standard scope.
Section IX qualifications
Covers qualification of welding, brazing and fusing procedures and personnel where invoked.
Reference table
Common ASME references for stainless systems
The edition required by the contract or jurisdiction governs. The current ASME catalog should be checked at the time of purchase.
| Reference | Primary role | Typical stainless procurement input | Do not use it alone for |
|---|---|---|---|
| ASME B31.3 | Process piping design, materials, fabrication, examination and testing | Fluid service, design conditions, material, joint and examination basis | Pipe dimensions or a complete material purchase specification |
| ASME B31.1 | Power piping systems | Design conditions, service, material and fabrication basis | A generic process-piping substitution |
| ASME B36.19-2022 | Stainless pipe outside diameter and schedule wall | NPS and schedule | Pressure rating or chemistry |
| ASME B16.5-2025 | Flanges and flanged fittings through NPS 24 | NPS, class, facing, material and temperature | All large-diameter flanges or piping design |
| ASME B16.9-2024 | Factory-made wrought buttwelding fittings | Size, schedule, type, material and marking | Forged socket-weld or threaded fittings |
| BPVC Section II, 2025 | Adopted materials and code properties | SA designation, grade, class and construction-code context | Construction rules by itself |
| BPVC Section IX, 2025 | Welding, brazing and fusing qualifications | Process, base material, filler and qualification scope | Product acceptance or design calculations |
ASME editions, addenda, code cases and local adoption can differ. The engineer or responsible authority must establish the governing code set.
Working method
Turn the project basis into a standards list
Traceability improves when each requirement is assigned to the document that actually controls it.
Identify jurisdiction and equipment
Determine whether the item is process piping, power piping, a pressure vessel, boiler or non-code product.
Freeze editions
Record the code edition, addenda and permitted code cases required by the contract or authority.
Map component standards
List B16, B36 and adopted material specifications for each line item.
Define quality evidence
State welding qualifications, examinations, pressure tests, MTCs, marking and authorized inspection.
Limits and escalation
Avoid common ASME procurement errors
ASME is not one specification
No single “ASME stainless steel standard” covers every product and service.
SA and ASTM need context
Many SA specifications are based on ASTM texts, but the code-adopted edition and construction rules govern code work.
Class is not schedule
Flange pressure class and pipe wall schedule describe different component attributes.
Edition matters
Do not silently substitute the newest edition when the project has frozen another edition.
Interactive planning aid
Choose a starting ASME reference
Select the item being specified. The result is the first reference to review, not the complete code stack.
Frequently asked questions
ASME stainless steel standards FAQ
No. It standardizes stainless pipe dimensions. A product specification such as an adopted SA specification defines material and manufacturing requirements.
B31.3 is a piping design and construction code; A312 is a pipe product specification. They address different layers of the requirement.
No. It provides component ratings and requirements within scope. System design must follow the governing piping code and consider all components and service conditions.
Not automatically. Use the edition adopted by the jurisdiction and specified by the contract, including any approved addenda or code cases.
Method, sources and review
Traceable sources and review status
Official dimensional standard for welded and seamless wrought stainless steel pipe.
Official scope and current edition for pipe flanges and flanged fittings.
Official ASME overview of process and power piping code families.
Official catalog for Section II materials, Section IX qualifications and construction sections.
This map summarizes scope only. Licensed code text, the project edition, jurisdiction and responsible engineer determine enforceable requirements.
ASME standards context
Read the ASME reference with the construction code and product scope.
An ASME material reference must be used with the applicable code edition, product specification, grade, dimensions, testing and acceptance clauses for the equipment in question.
- Code edition
- Product scope
- Acceptance clause
Visual process context
Connect the code reference to the supplied form and inspection route.
Reserve one image for the relevant product form and another for code, test or inspection evidence.
Engineering and sourcing support
Request stainless against a complete ASME code stack
Send equipment type, jurisdiction, code and edition, design conditions, component standard, material grade, welding, examination, documentation, quantity and destination.