FieldEngineersKitEngineering Reference & ASME Code Basis
1. Core Formula & Variable Definitions
MSS SP-97 (Integrally Reinforced Forged Branch Outlet Fittings) · ASME B31.3 (2022 Edition) · Para. 304.1.2 / 304.3.2 (branch design thickness & area replacement — screening note) · ASME B36.10M (matching Weldolet schedule OD / wall) · ASTM A105 / A182 (forging material families)
Drun,min ≤ Drun ≤ Drun,max · MSS SP-97 consolidated run size
tb = P · Dob2(S E W + P Y) · ASME B31.3 §304.1.2 screening
MSS SP-97 Weldolet / Sockolet / Threadolet envelope dimensions (A, B, d_hole, J)
Envelope dimensions A (height), B (base diameter), d_hole (header cutout), branch bore, and Sockolet socket depth J are taken from MSS SP-97 / Bonney Forge-style published charts by olet type and outlet rating. Weldolet uses schedule families (STD / XS / Sch 160); Sockolet and Threadolet use Class 3000 / 6000. Run NPS must fall inside the consolidated run-size band for Pass. Optional t_b uses B31.3 §304.1.2 with screening S for A105 (138 MPa) or A182 F316 (115 MPa), E = W = 1, Y = 0.4. Does not replace §304.3.2 area replacement.
- A (Outlet Height) — Vertical envelope from run OD to olet top / face (mm or in) — hero output.
- B (Base Diameter) — Outside diameter of the olet reinforcement base at the header (mm or in).
- d_hole (Header Cutout Diameter) — Recommended hole diameter in the run pipe for olet installation (mm or in).
- J (Socket Depth) — Sockolet socket engagement depth (mm or in). Not used on Weldolet / Threadolet.
- D_ob (Outlet Outside Diameter) — Branch pipe OD from B36.10M (Weldolet schedule) or screening OD for forged class outlets.
- t_b (Branch Design Thickness) — B31.3 §304.1.2 screening thickness for the outlet; export only — pad area is separate.
2. MSS SP-97 Lookup Rules & Scope
Field screening envelopes only. Confirm the current manufacturer dimensional chart and B31.3 reinforcement before purchase or fabrication.
Butt-weld olet ends match pipe schedule wall. STD ≈ Sch 40; XS ≈ Sch 80 for common carbon-steel sizes.
Forged pressure-class outlets (MSS SP-97 / B16.11 family). Socket depth J applies to Sockolet only.
Selected header NPS must lie between published runMin and runMax for that outlet. Outside range → Fail screening.
Pad / excess area A1–A5 checks remain in the Pipe Branch Reinforcement calculator.
Quick Reference Lookup Table
| Type | Run × Outlet | Rating | A | B | Note |
|---|---|---|---|---|---|
| Weldolet | 6 × 2 | STD | 38.1 mm | 58.7 mm | Default duty |
| Sockolet | 8 × 1.5 | 3000 | 33.3 mm | J = 12.7 mm | Socket depth |
| Weldolet | 12 × 4 | XS | 2.25 in | 4.88 in | Imperial |
| Threadolet | 4 × 1 | 3000 | 1.31 in | NPT 1 in | Threaded |
| Weldolet | 6 × 3 | STD | 44.5 mm | 84.1 mm | Larger outlet |
| Sockolet | 6 × 2 | 3000 | 38.1 mm | J = 15.7 mm | Class 3000 |
| Weldolet | 8 × 2 | XS | 42.9 mm | 65.1 mm | XS family |
| Threadolet | 6 × 1.5 | 3000 | 33.3 mm | NPT 1½ in | Threaded |
A / B from MSS SP-97 screening rows in this app. Confirm OEM chart; integrally reinforced fittings may still need B31.3 area checks on large/high-pressure duties.
3. Applicability & Fitting / Material Limits
Use for MSS SP-97 forged olet envelope lookup. Not a substitute for OEM charts, size-on-size specials, or formal reinforcement calculations.
| Group / Regime | Range / Condition | Limit / Criterion | Engineering Notes |
|---|---|---|---|
| Weldolet (BW) | — | — | Schedule-rated BW branch outlets. Default duty: NPS 6 run × NPS 2 STD on A105. |
| Sockolet (SW) | — | — | Class 3000 / 6000 socket-weld outlets with published socket depth J. |
| Threadolet (NPT) | — | — | Class 3000 / 6000 threaded outlets. End prep lists NPT size matching the outlet NPS. |
| A105 / A182 F316 | Screening S at entered T context | A105 138 MPa · F316 115 MPa | Forging material presets for t_b screening only — confirm Table A-1 / forging allowable at metal design temperature. |
Code Applicability & Safety Boundaries
- Does not certify MSS SP-97 manufacturing tolerances or OEM weight.
- Does not perform ASME B31.3 Para. 304.3.2 area replacement.
- Size-on-size and special run cradles may differ from reducing consolidated ranges.
4. Step-by-Step Worked Example
Field VerificationShowHide
Worked Example — Weldolet 6×2 STD (metric)
Look up a carbon-steel Weldolet on an NPS 6 header with an NPS 2 STD outlet for layout and cutout planning.
Select MSS SP-97 row
Check consolidated run size
Read cutout and bore
Optional t_b screen
5. How to look up MSS SP-97 olet dimensions
- 1
Choose olet type and rating
Weldolet → STD / XS / Sch 160. Sockolet or Threadolet → Class 3000 / 6000.
- 2
Enter run and outlet NPS
Header (run) size and branch outlet size. Confirm Pass on the consolidated run-size band.
- 3
Read A, B, d_hole (and J)
Hero shows height A. Rows list cutout, base diameter, bore, and Sockolet socket depth when applicable.
- 4
Carry to reinforcement if needed
High-pressure or large outlets: open Pipe Branch Reinforcement with the same run / branch NPS.
6. Frequently Asked Questions & Technical References
ShowHide
Weldolet ends are butt-weld and sized by pipe schedule (STD / XS / 160). Sockolet is a socket-weld forging sized by pressure class (3000 / 6000) with a published socket depth J.
No. Integrally reinforced fittings still need project confirmation against Para. 304.3. Use this chart for envelope / cutout dimensions, then run Pipe Branch Reinforcement when area replacement is required.
Reducing-olet screening rows often start the run band above the outlet NPS. Size-on-size cradles can differ — confirm the OEM chart before ordering.
End-prep notes list NPT matching the outlet NPS (e.g. NPS 1 → NPT 1 in) for Class 3000 / 6000 Threadolet screening.