ASME B16.9
Factory-made wrought buttwelding fittings
The dimensional standard for factory-made wrought buttwelding fittings — long- and short-radius elbows, tees, reducers, caps, stub ends and returns — from NPS ½ upward.
- Dimensional standards
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASME B16.9?
ASME B16.9 is the dimensional standard for factory-made wrought buttwelding fittings from NPS ½ to NPS 48 — long- and short-radius elbows, tees, reducers, caps, stub ends, crosses and returns. It sets centre-to-end dimensions, tolerances and marking; wall thickness matches the connecting pipe schedule. Short-radius elbows, formerly in ASME B16.28, were incorporated into B16.9 in 2001 and B16.28 was later withdrawn. Material comes from a specification such as ASTM A403, ASTM A234 or ASTM B366.
ASME B16.9 at a glance
| Sizes | NPS ½ – 48 |
|---|---|
| Fittings | LR (1.5D) and SR (1.0D) elbows, 45° elbows, returns, tees, crosses, reducers, caps, stub ends |
| Wall thickness | Matches the pipe schedule ordered |
| Ends | Bevelled for welding (ASME B16.25 weld-end preparation) |
| Material | Not set by B16.9 — e.g. A403, A234, A815, B366 |
| Replaces | ASME B16.28 (short-radius elbows), now withdrawn |
ASME B16.9 vs MSS SP-43 vs ASME B16.11
Three fitting standards with different jobs.
| Standard | Covers | Wall |
|---|---|---|
| ASME B16.9 | Buttweld fittings NPS ½ – 48 | Any schedule, matched to the pipe |
| MSS SP-43 | Light-wall corrosion-resistant buttweld fittings | Schedule 5S and 10S |
| ASME B16.11 | Forged socket-weld and threaded fittings NPS ⅛ – 4 | Rated by class (2000 – 9000) |
How to write ASME B16.9 on a purchase order
Name the product, size, material specification and grade, the dimensional standard and the certificate. An example line:
Illustrative only — sizes, tests, inspection level and any project values come from your purchase specification.
ASME B16.9 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition | Not yet confirmed against the publisher listing |
|---|---|
| Full-text verification | In progress — numerical requirements are not published on this page |
| Edition on your order | The edition named in your purchase order or design code governs — confirm it with your enquiry |
What to know before ordering to ASME B16.9
The points that decide whether material to ASME B16.9 is accepted at inspection.
- Wall thickness matches the pipe schedule the fitting is welded to.
- End preparation (bevel) follows ASME B16.25.
- Short-radius elbows, once in B16.28, are now part of B16.9.
Products made to ASME B16.9
How ASME B16.9 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Standards used with ASME B16.9
Same family
ASME B16.9 — questions buyers ask
What is ASME B16.9?
ASME B16.9 is the dimensional standard for factory-made wrought buttwelding fittings from NPS ½ to NPS 48 — long- and short-radius elbows, tees, reducers, caps, stub ends, crosses and returns. It sets centre-to-end dimensions, tolerances and marking; wall thickness matches the connecting pipe schedule. Short-radius elbows, formerly in ASME B16.28, were incorporated into B16.9 in 2001 and B16.28 was later withdrawn. Material comes from a specification such as ASTM A403, ASTM A234 or ASTM B366.
Is ASME B16.28 still valid?
No. Short-radius elbows were moved into ASME B16.9 in the 2001 edition and B16.28 was withdrawn. Orders that still cite B16.28 should be read as B16.9 short-radius elbows.
What is the difference between LR and SR elbows?
A long-radius elbow has a centre-line radius of 1.5 × nominal size; a short-radius elbow has 1.0 × nominal size. LR is the default; SR is used where space is tight and has higher pressure drop.
Does B16.9 set the fitting material?
No. Order the material separately, e.g. ASTM A403 WP316L for stainless or A234 WPB for carbon steel.
What is the difference between B16.9 and MSS SP-43?
SP-43 covers light-wall (Sch 5S / 10S) corrosion-resistant fittings, ordered as A403 CR grades; B16.9 covers all schedules and is the standard for pressure piping.
Does ASME B16.9 specify the material?
No. ASME B16.9 sets dimensions; the material comes from a separate specification such as ASTM A182, A105 or B564 for flanges, or A403 and B366 for fittings. A complete order names both.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026