ZNiBolt

Stud Bolts

Stud bolts for pressure flanges and machinery: ASTM A193 B7 / B7M fully threaded double-end studs supplied with ASTM A194 2H heavy hex nuts for oil, gas and chemical plant flanges, and DIN 938 / DIN 939 tap-end studs for engine and machinery housings. Finishes include zinc-nickel, PTFE (fluoropolymer) coating, HDG and plain.

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Stud Bolts we supply

A193 B7 Stud Bolt – representative photo

ASTM A193 B7 Stud Bolt with A194 2H Nuts

DIN 938/939 Tap-End Stud – representative photo

DIN 938 / DIN 939 Tap-End Stud

Stud Bolts: standards, sizes and options
Product / standardSizesGradesMaterialFinishesMOQ
ASTM A193 B7 / ASME B16.5 lengths
A193 B7 Stud Bolt
1/2" – 4"; M12 – M64B7, B7MAISI 4140 / 4142 alloy steelBlack oxide / phosphate, Zinc-nickel, Hot-dip galvanized, Zinc flake (Dacromet/Geomet type)500 pcs / size
DIN 938 / DIN 939
DIN 938/939 Tap-End Stud
M6 – M305.6, 8.8, 10.9Carbon steel; Alloy steelBlack oxide / phosphate, Zinc plated, Zinc-nickel500 pcs / size

Ordering stud bolts

MOQ
500 pcs per size (negotiable for trial orders)
Mixed sizes
Welcome in one order
Samples
Samples available — cost and lead time quoted per request
Lead time
15–25 days for standard parts; finishes such as HDG or Dacromet add a few days
Payment
T/T 30% deposit, 70% before shipment
Shipping
FOB Ningbo / CIF / DDP on request
Packaging
Cartons on pallets, or private-label boxes and bags
Documents
Material certificate, coating thickness and salt-spray reports on request
Custom
Drawings, non-standard sizes, coatings, marking and private-label packaging

To quote quickly, please send

  • Standard (e.g. DIN, ISO, ASTM) or drawing number
  • Size × length and thread pitch
  • Property class / grade and material
  • Finish and coating thickness (or the salt-spray hours you need)
  • Quantity per size and annual volume
  • Packaging and destination port

Finishes for stud bolts

Zinc-nickel and zinc are plated on our own line in Ningbo. Other finishes are applied by specialist coaters to the relevant standard.

FinishAppliedNotes
Black oxide / phosphateAvailableIndoor or oiled service
Zinc-nickelOur own line12–15 µm, clear or black passivation; 1,000 h (12 µm) to 1,440 h (15 µm) neutral salt spray
Hot-dip galvanizedAvailableISO 10684 / ASTM F2329; nuts tapped oversize to suit
Zinc flake (Dacromet/Geomet type)AvailableElectrolyte-free, no hydrogen embrittlement risk
Zinc platedOur own lineClear/blue, yellow or black passivation

For property class 10.9 and above, choose zinc flake, or zinc-nickel with hydrogen-embrittlement relief agreed at order stage.

Row of zinc-nickel electroplating tanks
Our zinc-nickel plating line. Salt spray: 12 µm ≈ 1,000 h, 15 µm ≈ 1,440 h (neutral salt spray to first red rust). How zinc-nickel compares

How to choose

B7 or B7M?
B7M is hardness-limited for sour (H2S) service per NACE MR0175. Use B7 for general high-temperature flange service.
Which coating for flange studs?
PTFE coating or zinc-nickel resist corrosion and ease removal; HDG for outdoor structural use.

Request a stud bolt quote

Send sizes and quantities — we reply with price, finish options and lead time within 24 hours.

We reply within 24 hours (China time). Your details are used only to answer this inquiry.

Stud Bolts FAQ

Do you supply studs with 2H nuts as sets?
Yes. B7 studs are normally supplied with two A194 2H heavy hex nuts each, packed per flange size.
Can you make studs to flange length tables?
Yes, to ASME B16.5 flange stud length tables or your list.

Technical guides

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