RAYCHIN LIMITED

Hex Bolts – Partial & Full Thread (DIN 931 / DIN 933 / ISO 4014 / ISO 4017)

Alloy 20 hex bolts manufactured to DIN 931 (partial thread), DIN 933 (full thread), ISO 4014, ISO 4017, and ASME B18.2.1 standards. Features a hex head for external wrenching, providing high torque capability and positive drive. Available in partial thread configuration for shear strength and alignment, or full thread configuration for maximum thread engagement. Ideal for high-temperature corrosive applications up to 538°C in pressure vessels, flange connections, and structural assemblies. Available in sizes from M6 to M100 (metric) and 1/4" to 4" (inch) in various lengths. Precision rolled threads for superior strength and corrosion resistance.

Heavy Hex Bolts (DIN 6914 / ASME B18.2.1)

Alloy 20 heavy hex bolts manufactured to DIN 6914, ASME B18.2.1 (heavy hex series), and ASTM A325/A490 dimensional standards. Features a larger head configuration providing increased bearing area for high-pressure flange connections and pressure vessel applications. Essential for API 6A and ASME B16.5 bolting assemblies in corrosive environments. The heavier head distributes load more effectively and resists dilation at elevated temperatures. Available with controlled hardness ≤ 35 HRC for NACE MR0175 sour service compliance. Sizes from 1/2" to 4" (M12 to M100). Supplied with matching Alloy 20 heavy hex nuts.

Flange Bolts (DIN 6921 / ISO 4162)

Alloy 20 flange bolts manufactured to DIN 6921, ISO 4162, and ASME B18.2.3.3M standards. Features an integrated flange under the head that provides a larger bearing surface, eliminating the need for separate washers. The flange distributes clamping load evenly and provides vibration resistance. Ideal for high-temperature corrosive applications up to 538°C in automotive, gas turbine, and industrial equipment. Available with serrated flange for anti-rotation. Precision rolled threads for superior fatigue life. Sizes from M6 to M36 (metric) and 1/4" to 1-1/2" (inch).

Carriage Bolts (DIN 603 / ISO 4018 / ASME B18.5)

Alloy 20 carriage bolts manufactured to DIN 603, ISO 4018, and ASME B18.5 standards. Features a domed head and square neck that prevents rotation during installation. Designed for high-temperature corrosive applications where access to the bolt head is limited. Ideal for structural connections, heat exchanger assemblies, and high-temperature ductwork. Available in UNC, UNF, and metric coarse/fine threads. Sizes from 1/4" to 1-1/2" (M6 to M36). Hot formed and precision machined options available. Square neck ensures positive locking during tightening.

Alloy 20 Bolts – API & NACE Compliant

Alloy 20 bolts certified to NACE MR0175 / ISO 15156 for sour service applications in oil and gas industry. Class D condition with controlled hardness ≤ 35 HRC per API 20F BSL2 & BSL3 requirements. Suitable for wellhead equipment, valve assemblies, subsea connections, and refinery applications exposed to H₂S environments. Available in all configurations with 100% hardness testing and impact testing per Class D requirements. 100% NDT available including PMI, UT, and MPI. API 6A closure bolts available with full traceability and material certifications per ASTM B473.

Custom & Specialty Alloy 20 Bolts

Need a special head style, unusual thread configuration, or custom length for your corrosive application? RAYCHIN engineers work with you to produce custom Alloy 20 bolts to your drawing. Options include T-head bolts, eye bolts, U-bolts, anchor bolts, and bolts with drilled heads for safety wiring. Expert heat treatment (solution annealed at 1030-1120°C) ensures optimum corrosion resistance. Manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS standards.

Metallurgical competence

Engineers on staff with deep expertise in nickel-based superalloys. We ensure proper solution annealing (1030-1120°C) for optimal corrosion resistance across all Alloy 20 bolts. Every heat is verified by in-house PMI testing to confirm chemistry. With 32-38% nickel and copper-molybdenum additions, our bolts provide exceptional resistance to sulfuric acid, phosphoric acid, and chloride stress corrosion cracking.

Global approvals & traceability

Our quality system is ISO 9001:2015 and AS9100D certified; we also comply with NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS. Full material traceability from melt to final packaging (EN 10204 3.1/3.2). Third-party inspections (ABS, DNV, Lloyds) available. All Alloy 20 bolts meet applicable ASTM B473, ASME SB473, NACE MR0175, and all relevant bolt standards.

Precision head forming & thread rolling

In-house CNC cold heading, hot forging, and precision thread rolling capabilities ensure consistent head dimensions and thread geometry. Precision rolled threads provide superior fatigue life and dimensional accuracy. Accurate hex heads for positive wrench engagement. 100% thread and dimensional inspection available. Controlled underhead fillet for improved fatigue resistance.

Custom solutions

Need a special head style, unusual thread configuration, or custom length for your corrosive application? Our engineering team works with you to produce custom Alloy 20 bolts to your drawing. We provide specialized surface treatments, passivation, and NACE MR0175 compliant processing per customer requirements.