Why can t_m differ from a pipe B31.3 t calculation?

B16.34 sizes the valve body with fixed S = 7000 psi and class designation P_c. B31.3 sizes pipe with material allowable stress S, joint efficiency E, and coefficient Y — different code paths.

Does Standard Class P-T match ASME B16.5?

For the same material group, B16.34 Standard Class ratings align with B16.5 Table 2. This Phase-1 extract covers Groups 1.1 and 2.2 from that shared basis.

Is Special Class included?

No. Special Class and Section 8 NDE / forged high-pressure rules are out of scope. Use the full ASME B16.34 text and OEM data for those valves.

ASME B16.34 Valve Wall Thickness & Pressure Rating — NPS 3 · Class 150 · A105 · 100 °F

Parameter	Value
Nominal pipe size (NPS)	3"
Pressure class	Class 150

Engineering Reference & ASME Code Basis

1. Core Formula & Variable Definitions

ASME B16.34-2020 Valves — Flanged, Threaded, and Welding End · ASME B16.34 §6.1 Minimum Wall Thickness · ASME B16.34 Table 3 Valve Body Minimum Wall Thickness · ASME B16.34 Table 2 Pressure-Temperature Ratings (Standard Class) · ASME B16.34 Mandatory Appendix VI Basis for Minimum Wall Thickness Equations

t_m = 1.5 · [P_c · d / (2S − 1.2 P_c)] + A

p_max = f_B16.34(Class, Material Group, T) · p_hydro = 1.5 · p_amb,38°C

ASME B16.34-2020 Mandatory Appendix VI (S = 7000 psi, A = 0.10 in / 2.54 mm) · Table 3 discrete check · Table 2 Standard Class P-T

S 7000 psi (48.3 MPa)A 0.10 in (2.54 mm)Default duty NPS 4 · Class 300 · 5.91 mmHydro 1.5 × ambient rating

Wall thickness uses the Appendix VI US-customary equation with class designation pressure P_c (psi) and fixed S = 7000 psi. Table 3 values in this tool are the same equation evaluated at discrete inside diameters. Standard Class P-T for Groups 1.1 and 2.2 matches the ASME B16.5 Table 2 Phase-1 extract. Special Class and Section 8 NDE rules are out of scope.

t_m (Minimum body wall thickness) — Required valve body wall from Appendix VI / Table 3 for the selected class and inside diameter d.
d (Inside / port diameter) — Valve flow-passage inside diameter used in Appendix VI (mm or in).
P_c (Class designation pressure) — Class rating reference pressure: 150, 300, 600, 900, 1500, or 2500 psi.
S (Appendix VI stress factor) — Fixed 7000 psi basis in Mandatory Appendix VI wall equations.
p_max (Allowable pressure at temperature) — Standard Class P-T rating from ASME B16.34 Table 2 for the material group and design temperature.
p_hydro (Hydrostatic shell test pressure) — 1.5 × ambient (38 °C) Standard Class rating for factory shell test screening.

2. Screening Assumptions

Standard Class body wall and P-T screen for metal valves. Neck detailing, casting/forging tolerance, and Special Class rules are out of scope.

Wall basisAppendix VI + Table 3 discrete check

Governing t_m is the greater of the closed-form Appendix VI result and the interpolated Table 3 discrete grid (same equation basis).

Default dutyNPS 4 · Class 300 · d = 102 mm · 200 °C · 35 bar · Group 1.1

Hero t_m = 5.91 mm; p_max = 43.8 bar (Pass). Hydro shell screen = 1.5 × 51.1 bar = 76.7 bar.

P-T Phase-1 groups1.1 and 2.2 tabulated; 1.2 proxy; 1.9 unavailable

Groups 1.1 / 2.2 use the published Standard Class extract (aligned with B16.5 Table 2). Group 1.2 (WCC) uses Group 1.1 as a conservative proxy. Group 1.9 (WC6) wall still screens; P-T is marked unavailable.

Out of scopeSpecial Class · Section 8 NDE · soft-seat trim

Forged high-pressure valves with additional NDE and Special Class ratings require the full ASME B16.34 Section 8 path and OEM charts.

Quick Reference Lookup Table

Appendix VI / Table 3 wall check — Class 300 inside diameter vs t_m (metric)
Inside d (mm)	t_m (mm)	P_c (psi)	Basis
50	4.19	300	Appendix VI
80	5.18	300	Appendix VI
100	5.84	300	Appendix VI
102	5.91	300	Default duty
150	7.49	300	Appendix VI
200	9.14	300	Appendix VI
250	10.79	300	Appendix VI

Values are Appendix VI equation results (S = 7000 psi, A = 0.10 in) rounded for field screening. Confirm published ASME B16.34 Table 3 for purchase documents.

3. Material Groups & Temperature Limits

ASME B16.34 Table 1A material groups used for Standard Class P-T screening in this Phase-1 extract.

Material Group	Temperature Range	Allowable Stress / Limit	Engineering Notes
Group 1.1 — A105 / A216 WCB	−29 to 538 °C (Class-dependent)	Standard Class Table 2-1.1	Default carbon-steel forged / cast body group.
Group 1.2 — A216 WCC	Same band as Group 1.1 (proxy)	Phase-1 uses Group 1.1 curve	Conservative screening proxy only — confirm published Table 2-1.2 for purchase.
Group 2.2 — A351 CF8M / 316	−29 to 538 °C (Class-dependent)	Standard Class Table 2-2.2 (Phase-1: Class 150–600)	Austenitic stainless cast / forged bodies in Phase-1 extract.
Group 1.9 — A217 WC6	P-T Phase-1 unavailable	Wall screen only (Appendix VI)	Load full ASME B16.34 Table 2-1.9 before accepting Cr-Mo P-T duty.

Code Applicability & Safety Boundaries

Standard Class only — Special Class ratings are not tabulated here
Confirm OEM casting drawings for neck thickness beyond pure t_m

4. Step-by-Step Worked Example

Field VerificationShow

Worked example — NPS 4 · Class 300 · WCB · 200 °C

Standard Class carbon-steel gate/globe body, NPS 4, Class 300, port inside diameter 102 mm, design 35 bar at 200 °C, material Group 1.1 (A105 / WCB).

NPS / Class:4 / 300d:102 mmT / P:200 °C / 35 barMaterial:Group 1.1 A105 / WCB

Appendix VI wall

t_m = 1.5 · [300 · (102/25.4) / (2·7000 − 1.2·300)] + 0.10 in → mm

Result:t_m = 5.91 mm (Table 3 check agrees)

P-T rating at 200 °C

Interpolate Standard Class Group 1.1 · Class 300 table

Result:p_max = 43.8 bar

Duty check & hydro

P_design ≤ p_max; p_hydro = 1.5 · p_amb(38 °C)

Result:35 ≤ 43.8 → Pass; p_hydro = 76.7 bar

Conclusion: Required minimum body wall is t_m = 5.91 mm. Allowable pressure at 200 °C is 43.8 bar (Pass vs 35 bar design). Factory shell hydro screen is 76.7 bar. Confirm OEM casting drawing for neck and casting allowance beyond this pure t_m.

5. How to screen ASME B16.34 valve body wall and P-T rating

1
Select NPS, class, and inside diameter
Enter the valve NPS, Standard Class (150–2500), and the port / inside diameter d in mm or inches.
2
Choose material group and duty
Pick the B16.34 Table 1A group and enter design temperature and working pressure in the active unit system.
3
Read t_m and p_max
Hero shows governing t_m. Badges show p_max at temperature and Pass / Overpressure vs design pressure.
4
Export or continue
Export CSV/PDF for the duty pack, or carry NPS/class/temperature to pipe wall, flange dimension, or valve Cv tools.

6. Frequently Asked Questions & Technical References

Show

A field screen of Standard Class valve body minimum wall t_m from Appendix VI / Table 3, plus Table 2 P-T allowable pressure and a 1.5× ambient hydro shell test estimate.

ASME B16.34 Valve Wall Thickness & Pressure Rating Calculator

NPS 3 · Class 150 · A105 · 100 °F valve wall & P-T rating summary

1. Core Formula & Variable Definitions

2. Screening Assumptions

Quick Reference Lookup Table

3. Material Groups & Temperature Limits

Code Applicability & Safety Boundaries

4. Step-by-Step Worked Example

Worked example — NPS 4 · Class 300 · WCB · 200 °C

Appendix VI wall

P-T rating at 200 °C

Duty check & hydro

5. How to screen ASME B16.34 valve body wall and P-T rating

6. Frequently Asked Questions & Technical References

ASME B16.34 Valve Wall Thickness & Pressure Rating Calculator

NPS 3 · Class 150 · A105 · 100 °F valve wall & P-T rating summary

1. Core Formula & Variable Definitions

2. Screening Assumptions

Quick Reference Lookup Table

3. Material Groups & Temperature Limits

Code Applicability & Safety Boundaries

4. Step-by-Step Worked Example

Worked example — NPS 4 · Class 300 · WCB · 200 °C

Appendix VI wall

P-T rating at 200 °C

Duty check & hydro

5. How to screen ASME B16.34 valve body wall and P-T rating

6. Frequently Asked Questions & Technical References

What is an ASME B16.34 valve wall thickness calculator?

Why can t_m differ from a pipe B31.3 t calculation?

Does Standard Class P-T match ASME B16.5?

Is Special Class included?