ASME B16.5 & B16.47 Titanium Flanges: WN, RF/RTJ, Class 150–2500, Series A/B

Published by Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd on 2026-10-21

ASME B16.5 & B16.47 Titanium Flanges: Weld Neck, Slip-On, Blind, RF/RTJ, Class 150–2500 & Series A/B

Table of Contents

• 1. B16.5/B16.47 vs ASTM B381: Who Does What
• 2. ASME B16.5: NPS 1/2–24
• 3. Flange Types: WN, SO, Blind, Lap-Joint, Threaded, LWN
• 4. Faces: RF, FF, RTJ, Tongue & Groove
• 5. Class 150 / 300 / 600 / 900 / 1500 / 2500
• 6. Bore & Schedule Matching
• 7. ASME B16.47: NPS 26–60, Series A vs Series B
• 8. Machining Titanium Flanges Without Galling
• 9. How to Write a Titanium Flange RFQ
• 10. Flange Procurement Mistakes
• 11. Our Titanium Flange Capability
• 12. FAQs
• 13. Related Standards

1. B16.5 / B16.47 vs ASTM B381: Who Does What

A correct PO reads like this:Flange forged to ASTM B381 F-2, machined to ASME B16.5 Class 150 WN RF, NPS 4", Sch 10S, annealed, pickled.

2. ASME B16.5: NPS 1/2–24

• Size range: NPS 1/2" to 24" (DN 15 to DN 600)
• Classes: 150, 300, 400, 600, 900, 1500, 2500
• Face types: RF, FF, RTJ, T&G, male-female
• Flange types: WN, SO, BL, LJ, SW, TH, LWN
• Material: titanium forgings per B381; bar-machined only for low-risk small SO flanges

For titanium chemical/marine lines, Class 150 RF Sch 10S and Class 300 RF Sch 10S/40S are the most common. [4](@ref)

3. Flange Types: WN, SO, Blind, Lap-Joint, Threaded, LWN

4. Faces: RF, FF, RTJ, Tongue & Groove

• Raised Face (RF): default; pairs with spiral-wound / sheet gaskets
• Flat Face (FF): full-face gaskets; used against cast iron / FRP equipment
• Ring Type Joint (RTJ): metal ring gasket, Class 600+ and hydrocarbon service; B16.47 Series A supports RTJ, Series B does not [3,6](@ref)
• Tongue & Groove / Male-Female: confined gasket, less common in titanium process lines

Titanium is soft and work-hardens. RF finish must be clean, scratch-free, and free of embedded iron. A scratched titanium RF face is a future leak path.

5. Class 150 / 300 / 600 / 900 / 1500 / 2500

ASME “Class” is not the same as pressure in bar/psi. The allowable pressure depends on material and temperature. For titanium:

• Class 150: low-pressure seawater, brine, utility lines
• Class 300: chemical process, heat exchanger nozzles
• Class 600: higher-pressure reactors, pumps, compressors
• Class 900–2500: high-pressure hydrocarbon / aerospace ground support

Always read the project pressure-temperature rating table for the actual titanium grade, not carbon-steel A105 numbers.

6. Bore & Schedule Matching

• WN flange bore should match pipe ID/OD and schedule (Sch 5S / 10S / 40S / 80S)
• Don’t put a Sch 10S bore on Sch 80S pipe — you create a step and turbulence/erosion
• Stub end + lap-joint flange: stub end wall matches pipe; flange bore is oversized
• For B363 fittings: flange bore, pipe wall, and fitting wall must be in the same schedule family

7. ASME B16.47: NPS 26–60, Series A vs Series B

Above NPS 24, ASME B16.5 stops and B16.47 takes over for weld neck and blind flanges NPS 26–60. [6](@ref)

Series A and Series B are not interchangeable. Same NPS/Class can have different OD, bolt circle, and bolt count. [3,8](@ref)

8. Machining Titanium Flanges Without Galling

• Sharp carbide tooling, low speed, positive rake, flood coolant
• No carbon-steel chips in the titanium machining area
• Chamfer/bevel per WPS; protect RF/RTJ face after cutting
• Deburr without smearing iron; chloride-free cleaning only
• PMI / XRF to confirm grade before marking
• Permanent mark: grade + NPS + class + facing + heat no. + PO

9. How to Write a Titanium Flange RFQ

Weak: "Titanium flange 4 inch 150 lb"

Strong: Flange forged to ASTM B381 F-2, machined to ASME B16.5 Class 300 Weld Neck RF, NPS 4", bore Sch 10S, annealed, pickled, PT after machining, EN 10204 3.1, heat no. on hub

Must specify:

1. Material standard: ASTM B381 F-2 / F-5 / F-7 / F-12
2. Dimensional standard: ASME B16.5 or B16.47
3. Type: WN / SO / BL / LJ / SW / TH / LWN
4. Class: 150 / 300 / 600 / 900 / 1500 / 2500
5. Size: NPS + bore schedule
6. Face: RF / FF / RTJ / T&G
7. Large flange: B16.47 Series A or Series B
8. Condition: annealed, pickled, machined face protected
9. NDE: PT, UT, PMI, dimensional
10. Certificate: 3.1 / 3.2

10. Flange Procurement Mistakes

11. Our Titanium Flange Capability

• Material: ASTM B381 F-2 / F-5 / F-7 / F-9 / F-12 / F-23
• B16.5: NPS 1/2–24, Class 150–2500, WN/SO/BL/LJ/SW/TH/LWN
• B16.47: NPS 26–60, Series A & Series B, WN & Blind
• Faces: RF, FF, RTJ, T&G
• Bore: Sch 5S / 10S / 40S / 80S, custom bores
• Finish: annealed, pickled, face-protected, export packed
• Paired with: B861/B862 pipe, B363 fittings, B863 ERTi filler
• Inspection: PMI/XRF, PT, dimensional, UT on request
• Cert: EN 10204 3.1 / 3.2, TPI (SGS/LR/DNV/TÜV) on request

We deliver bolt-up-ready titanium flanges, not just machined discs.

12. FAQs

Q: Is a titanium flange “B16.5 Gr.2”?

Loosely yes, strictly no. B16.5 is dimensions; Gr.2/F-2 is material. Write “B381 F-2, machined to B16.5”.

Q: Can titanium flanges use carbon-steel bolts?

They can, but galvanic corrosion is a risk in seawater. Use titanium, Hastelloy, or insulated/non-metallic washer sets with proper design.

Q: When do I need RTJ instead of RF?

High-pressure / hydrocarbon / toxic-service lines often use RTJ. For titanium chemical lines, RF + spiral-wound gasket is very common.

Q: What’s the max size in B16.5?

NPS 24". Above that, use ASME B16.47 (NPS 26–60). Above NPS 60, flanges are custom-engineered. [6](@ref)

Q: Are B16.47 Series A and B interchangeable?

No. Different OD, bolt circle, bolt count/size. Never mix them. [3,8](@ref)

13. Related Standards

• ASTM B381 Titanium Forgings — forged flange blanks
• ASTM B861 Titanium Seamless Pipe — WN flange matching pipe
• ASTM B862 Titanium Welded Pipe — large lines + B16.47 flanges
• ASTM B363 Titanium Fittings — elbows/tees/reducers for spools
• ASTM B863 Titanium Wire — ERTi filler for flange welds
• ASTM B348 Titanium Bar — small SO/SW flange stock
• ASTM B265 Titanium Plate — plate-source references
• ASTM B338 Titanium Tubes — exchanger nozzles/flanges
• Titanium Standards Hub — full ASTM/ASME series

Request Titanium Flange Quotation

Send us:

• Material: ASTM B381 F-2 / F-5 / F-7 / F-12
• Standard: ASME B16.5 or B16.47 Series A/B
• Type: WN / SO / BL / LJ / SW / TH / LWN
• Class + NPS + bore schedule
• Face: RF / FF / RTJ
• NDE + certificate (PMI, PT, UT, 3.1 / 3.2)

We reply within 4 business hours with dimensional check, facing options, and lead time.