MSS SP-97
Integrally reinforced forged branch outlet fittings (olets)
Covers integrally reinforced forged branch-outlet fittings — weldolets, sockolets, threadolets and similar — welded onto a run pipe to make a branch connection.
- Dimensional standards
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is MSS SP-97?
MSS SP-97 is the standard for integrally reinforced forged branch-outlet fittings — the weld-on outlets (often called weldolets, sockolets and threadolets) used to take a branch off a run pipe without a tee. It covers socket-welding, threaded and buttwelding ends. Material is ordered separately, for example ASTM A182 or ASTM A105.
MSS SP-97 at a glance
| Products | Forged branch outlets — buttweld, socket-weld and threaded ends |
|---|---|
| Use | Branch connections on larger run pipe |
| Material | Named separately |
Branch outlet types
| Type | Branch end | Typical use |
|---|---|---|
| Buttweld outlet | Bevelled for butt weld | Process branches, matched to branch schedule |
| Socket-weld outlet | Socket | Small-bore branches, rated by class |
| Threaded outlet | NPT thread | Instrument and vent connections |
How to write MSS SP-97 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.
MSS SP-97 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 MSS SP-97
The points that decide whether material to MSS SP-97 is accepted at inspection.
- The outlet is sized to the branch and matched to the run pipe size.
- Material follows A182, A105 or B564.
- Olets replace a full tee when the branch is much smaller than the run.
How MSS SP-97 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 MSS SP-97
Same family
MSS SP-97 — questions buyers ask
What is MSS SP-97?
MSS SP-97 is the standard for integrally reinforced forged branch-outlet fittings — the weld-on outlets (often called weldolets, sockolets and threadolets) used to take a branch off a run pipe without a tee. It covers socket-welding, threaded and buttwelding ends. Material is ordered separately, for example ASTM A182 or ASTM A105.
Is a weldolet the same as an MSS SP-97 fitting?
"Weldolet" is a trade name for a buttweld branch outlet; SP-97 is the standard that covers this fitting type.
Does MSS SP-97 specify the material?
No. MSS SP-97 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