Question 1

What documentation is included with each shipment?

Accepted Answer

Every LOKRON shipment includes an EN 10204 Type 3.1 Material Test Report (MTR), dimensional inspection certificate, and — for EU-bound shipments — a PED Declaration of Conformity. NACE MR0175/ISO 15156 compliance letters are available for sour-service grades (B7M, L7M).

Question 2

Can LOKRON supply special alloys and non-standard thread forms?

Accepted Answer

Yes. Our custom manufacturing covers Duplex 2205, Super-Duplex 2507, Inconel 625/718, Hastelloy C276, and Monel K-500. Thread forms including UNF, BSPP, API, Acme, and metric fine threads are produced to drawing with ±0.01mm CNC tolerance.

Question 3

What is the difference between ASTM A193 B7 and B7M?

Accepted Answer

B7 and B7M are the same chromium-molybdenum alloy (4140/4142) but with different heat treatment. B7M is tempered to a reduced maximum hardness of 22 HRC (237 HB) to comply with NACE MR0175/ISO 15156 sour-service requirements where hydrogen sulfide (H₂S) is present.

Question 4

What is the lead time for ASTM A193 B7 stud bolts?

Accepted Answer

Standard ASTM A193 B7 stud bolts in common sizes (M16–M36) are typically available ex-stock or within 5–10 working days with 3.1 MTR. Special sizes, exotic grades (B16, B8M Class 2), or large-volume orders require 3–6 weeks. Custom alloy items (Inconel, Duplex) require 4–8 weeks from material procurement.

Question 5

Does LOKRON supply EN 10204 Type 3.2 material test reports?

Accepted Answer

Yes. EN 10204 Type 3.2 (dual-witnessed, third-party inspector) MTRs are available on request for critical applications requiring independent verification. Type 3.1 is standard on all LOKRON shipments. Third-party inspection by SGS, Bureau Veritas, or Intertek can be arranged for any order.

Question 6

What surface treatments are available for stud bolts used in offshore or subsea applications?

Accepted Answer

For offshore and subsea applications, LOKRON offers hot-dip galvanising to ASTM A153 (85–100 μm zinc coating), PTFE/Xylan fluoropolymer coating (reduces galling, K-factor 0.10–0.12), Dacromet (zinc-aluminium flake coating, no hydrogen embrittlement risk), and electroless nickel plating. For subsea connectors, we recommend Xylan 1424 or Molykote-based coatings — contact our technical team for application-specific selection.

Question 7

Are ASTM A193 B7 stud bolts suitable for sour gas (H₂S) service?

Accepted Answer

No — standard B7 (maximum 35 HRC hardness) is not approved for sour service. Where hydrogen sulfide partial pressure exceeds 0.0003 MPa (0.05 psia) per NACE MR0175/ISO 15156, B7M must be specified instead. B7M is the same 4140/4142 Cr-Mo alloy but heat-treated to a maximum of 22 HRC (237 HB), satisfying NACE requirements. LOKRON supplies B7M with full NACE compliance documentation.

Question 8

Does LOKRON ship internationally and what are the typical shipping terms?

Accepted Answer

Yes — LOKRON ships to Europe, the Middle East, Southeast Asia, Australia, and North America. Standard shipping terms are FOB Suzhou or CIF destination port. All export orders include commercial invoice, packing list, certificate of origin (Form E for ASEAN, EUR.1 for EU), and EN 10204 3.1 MTRs. Dangerous goods classification does not apply to standard fasteners. Typical ocean freight transit: UK/Europe 25–35 days, Middle East 20–28 days, Australia 18–25 days.

Question 9

What are the torque values for ASTM A193 B7 stud bolts on ASME B16.5 flanges?

Accepted Answer

Torque values depend on flange pressure class, bolt size, and lubrication condition. For a 4" Class 600 flange (⅞" B7 studs, 8 bolts) with light oil (K=0.17), the target torque at 50% SMYS is approximately 230 N·m per bolt. For a 6" Class 900 flange (1¼" B7 studs, 12 bolts), target torque is approximately 680 N·m per bolt. Always apply the ASME PCC-1 cross-bolt tightening sequence (snug tight → 50% → 100% → clockwise verification), and conduct a hot retorque after the first thermal cycle to compensate for gasket relaxation. See our stud bolt torque chart guide for the full ASME B16.5 Class 150–2500 reference table.

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