Cast Steel SPM Chock JIS F 2030 Type A | Bulwark-Mounted Towing Chock for Single

Product Specification

Cast Steel SPM Chock JIS F 2030 Type A | Bulwark-Mounted Towing Chock for Single Point Mooring

Product Overview

The JIS F 2030 Type A cast steel SPM chock is a bulwark-mounted guide for vessels equipped for single point mooring. Installed at the bow bulwark, it provides a defined passage with rounded contact surfaces for the SPM mooring line or tanker-end chafe chain as specified by the vessel arrangement. The chock guides the line through the hull opening and transfers local contact reactions into the welded and reinforced bow structure.

Type A covers nominal sizes 400 to 800 with calculated masses from 210 to 880 kg. Selection should not be based on opening size alone. The actual SPM hawser and chafe-chain arrangement, line or chain diameter, design load, lead direction, bulwark reinforcement, weld detail, casting material, heat treatment, preheating procedure, surface finish, inspection scope, and class requirement should be confirmed before production. This product is a guide chock and should not be described as the chain stopper.

Quick Specifications

• Product type: Cast steel SPM chock → guides the single point mooring line or specified chafe-chain assembly through the bow bulwark.
• Standard and type: JIS F 2030-1978 Type A → supplied reference for Type A geometry, nominal size, dimensions, reference rope range, and calculated mass.
• Nominal size range: 400 / 500 / 600 / 700 / 800 → five standard sizes for different bow openings and SPM arrangements.
• Reference line range: Wire rope 50-132 mm, manila rope 30-70 mm, and nylon rope 80-120 mm → reference values only; final selection follows the actual SPM system specification.
• Calculated mass: 210-880 kg → relevant to shipyard handling, transport planning, installation support, and welding sequence.
• Installation: Bulwark welded arrangement → hull opening, lead direction, local reinforcement, weld profile, and access for welding and inspection require drawing confirmation.
• Material options: Cast C-Mn steel, cast stainless steel, or approved low-temperature special steel → exact grade, weldability, impact properties, and heat treatment are project-specific.
• Quality focus: Rounded contact surface, dimensional control, heat-treatment records, weld-zone preparation, and MT according to the agreed inspection plan.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm JIS F 2030 Type A and nominal size 400, 500, 600, 700, or 800 according to the approved vessel bow arrangement.

Step 2: Confirm the actual contact medium: SPM hawser, wire rope, synthetic rope, or tanker-end chafe chain, including diameter, chain size, construction, and terminal requirement.

Step 3: Provide the design load basis, lead angle, vertical and horizontal load directions, chain-stopper location, and the relationship between the chock and the complete SPM mooring arrangement.

Step 4: Confirm bulwark opening, available installation space, cast-body orientation, local deck / bulwark reinforcement, weld profile, access, and replacement constraints.

Step 5: Confirm casting grade, low-temperature or ice-class requirement, heat treatment, weldability, approved WPS / PQR, preheat requirement, and post-weld inspection.

Step 6: Confirm surface treatment, contact-surface finishing, MT extent and acceptance criteria, material traceability, class society, witnessing, and certificate scope.

Step 7: Provide quantity, vessel type, installation drawing, SPM system specification, reference photos, destination, required delivery time, and packing restrictions.

Structure

Cast steel Type A body | Over-type SPM passage | Rounded line-contact radii | Bulwark welded interface | Reinforced hull opening | Controlled weld-adjacent casting zone | Shop primer or specified stainless-steel finish

Casting, Welding & Engineering Advantages

• The large cast-body opening and rounded contact radii provide a continuous guide surface for the specified SPM line or chafe-chain path and help avoid sharp local contact at the bow opening.
• Casting geometry allows the opening, side walls, transitions, and weld interface to be produced as an integrated load-transfer form; final dimensional acceptance should follow the approved drawing.
• Rope- and chain-contact surfaces are dressed and smoothed after casting. The finish should remain industrial and traceable, without removing section thickness or altering the standard profile.
• Heat treatment should follow the selected casting grade and project specification. Material properties, heat-treatment condition, and impact-test requirements must be confirmed before manufacture.
• The cast body may require controlled preheating before welding to the ship structure. Preheat temperature, interpass control, consumables, welding sequence, and acceptance criteria must follow an approved WPS / PQR and the actual casting chemistry and thickness.
• Magnetic particle testing can be applied to specified cast and weld-adjacent areas to identify relevant surface-breaking indications. Examination coverage and acceptance criteria should be agreed rather than described as zero-defect casting.
• The chock transfers line-contact reactions into the bulwark and adjacent deck structure. Local reinforcement, load direction, weld length, and structural continuity remain part of the vessel design and class approval.

Custom Attributes

• Standard: JIS F 2030-1978 → supplied dimensional reference; current project acceptance and required edition should be confirmed.
• Type: Type A / over type as supplied → bulwark-mounted SPM guide configuration for the vessel bow arrangement.
• Nominal Size: 400 / 500 / 600 / 700 / 800 → select by approved opening, line or chain interface, and vessel drawing.
• Material: Cast C-Mn steel / cast stainless steel / approved special steel → exact grade, heat treatment, low-temperature properties, and weldability require confirmation.
• Installation: Welded to reinforced bow bulwark structure → weld detail, preheating, access, and structural support follow the shipyard drawing and WPS.
• Contact Surface: Rounded and dressed → surface condition should reduce sharp local contact without changing the standard profile.
• Inspection: MT according to project requirement → examination area, procedure, acceptance level, witness point, and report format are confirmed before order.
• Certificate Requirement: Available according to project scope → class certificate, material certificate, maker documentation, and inspection witnessing are not assumed as default.

How It Works

SPM hawser or chafe-chain assembly approaches the bow → The line passes through the rounded Type A chock opening → The smooth cast surface controls the lead and reduces sharp local contact → Contact reactions pass through the cast body and welded interface into the reinforced bulwark / deck structure → The separate chain stopper or securing arrangement retains the system as specified

Applications

Tankers equipped for single point mooring | SPM terminal operations | Bow bulwark mooring stations | Tanker-end chafe-chain arrangements | Newbuilding projects | Standard replacement and conversion projects

Certifications & Advantages

Material certificates, heat-treatment records, MT reports, dimensional inspection, maker documentation, class inspection, and other certificates can be arranged according to the project specification, agreed inspection scope, material traceability, and class approval procedure.

Certification: CCS, NK, BV, ABS, DNV, LR, KR, IRS, RS, RINA, CRS, Makers Test Certificate.

Drawing & Photos

FAQ

Q1: Is the JIS F 2030 Type A SPM chock the same as a chain stopper?

A1: No. The chock provides the guided passage and contact surface at the bow bulwark. The chain stopper or other securing device is a separate component that retains the chafe chain or mooring arrangement. Their positions, load paths, and interfaces should be checked together on the vessel drawing.

Q2: Can the nominal size be selected only from the reference rope diameter table?

A2: No. The reference rope table supports preliminary comparison only. Final selection should consider the actual SPM hawser or chafe-chain specification, design load, lead direction, opening geometry, contact radius, chain-stopper arrangement, bulwark reinforcement, and class requirement.

Q3: What welding and casting information is required before quotation?

A3: Confirm the exact casting grade, heat-treatment condition, chemistry or carbon-equivalent information, minimum design temperature, WPS / PQR, preheat and interpass requirements, weld detail, MT scope, acceptance criteria, material certificates, class witnessing, and the approved bow installation drawing.