11–30 mm Hatch Cover Pull Chain for TTS / MacGregor Chain-Drive Systems | Welded Studless Replacement Chain

11–30 mm Hatch Cover Pull Chain for TTS / MacGregor Chain-Drive Systems | Welded Studless Replacement Chain

Product Overview

This hatch cover pull chain is an independently supplied welded studless operating chain for selected chain-driven cargo hatch cover systems. It transfers drive force between the chain wheel and the moving hatch cover panel during opening and closing. The product is available in nominal bar diameters from 11 to 30 mm, including several A, B and C link-geometry variants.

TTS and MacGregor hatch covers have been supplied with different chain-drive layouts, including single-chain and two-sided arrangements. A replacement chain must therefore match the original link pitch, link width, wheel-pocket geometry, total link count, end connections and tensioning arrangement—not only the nominal diameter. Unless a quotation expressly states OEM supply, this product should be presented as a compatible

replacement manufactured to an approved drawing or verified sample.

Quick Specifications

• Product function: Hatch cover pull / operating chain → transmits motion within a chain-driven hatch cover system; not a lifting, mooring, anchor or cargo-securing chain.
• Nominal size range: 11 to 30 mm → includes 14A / 14B, 16A / 16B, 18A / 18B, 20A / 20B and 22A / 22B / 22C variants.
• Construction: Studless open-link welded chain → link geometry must match the existing pocket wheel, guide path and terminal connection.
• Proof load range: 57 to 399 kN → acceptance or manufacturing test value from the supplied table, not the allowable operating pull.
• Breaking load range: 116 to 798 kN → failure-limit value; must not be published as SWL or operating capacity.
• Approximate mass: 2.39 to 18.22 kg/m → relevant to replacement handling, total chain weight, pair matching and drive-system inertia.
• Supply form: Exact link count, cut length, matched pair, joining link and terminal fittings → confirmed from the hatch cover drawing or existing sample.
• Surface protection: Black coating, conventional galvanizing or hot-dip galvanizing → selected only after confirming dimensional fit, steel grade, welding and post-treatment requirements.

Main Technical Parameters

The source data are reproduced below without silently changing any values. The width column is shown as “Link Width Dimension” because the source describes it as outside width, but several values are smaller than the nominal bar diameter. The measurement basis must be confirmed from the original chain drawing.

Replacement Identification & Compatibility

Successful replacement starts with equipment identification, not with chain diameter alone. The preferred inquiry package is the original TTS / MacGregor drawing or spare-part reference together with photographs and measured dimensions from an unworn link.

Link Geometry & Drive Matching

• Nominal diameter alone does not define compatibility. A / B / C variants at the same diameter have different link lengths, widths and mass and must be treated as separate products.
• The link pitch must match the pocket-wheel pitch so that load is transferred through the intended contact area instead of at one edge of the link.
• The verified width must provide clearance through guides and around wheel pockets without allowing excessive lateral movement.
• Straightness, link twist and dimensional consistency affect how the chain enters and leaves the drive wheel; these points should be included in dimensional inspection.
• For two-sided drives, matched link count and total length help maintain panel alignment. Replacement of only one side should be evaluated against wear and elongation on the remaining chain.

Manufacturing, Welding & Heat Treatment

The chain is manufactured as a welded open-link product. The exact steel grade, welding method, heat treatment and dimensional tolerances should be tied to the approved chain drawing and required load table.

• Material selection should be based on required proof and breaking loads, weldability, toughness, corrosion exposure and any galvanizing process.
• The user-supplied range from Q235 to CM690 is too broad to present as interchangeable. Exact grade designation, chemistry and mechanical properties must be confirmed for each chain size.
• Weld profile should be smooth and consistent without local undercut, overlap or excessive reinforcement that could interfere with wheel engagement.
• Heat treatment, when specified, should be controlled and documented because it affects strength, toughness, dimensional stability and coating suitability.
• Each production batch should maintain traceability between material heat, manufacturing lot, test sample and finished chain length.

Proof Testing, Inspection & Documentation

Proof load and breaking load serve different purposes. Proof testing verifies that the finished chain withstands the agreed acceptance load without unacceptable permanent deformation. Breaking-load verification is normally performed on a representative sample according to the agreed test plan.

• Dimensional inspection: bar diameter, pitch, width, link shape, straightness, twist, total length and end-connection dimensions.
• Visual and weld inspection: surface condition, weld profile, cracks, laps, sharp edges, coating damage and identification marks.
• Proof-load test: scope, loading rate, holding requirement, permanent set and acceptance criteria to be confirmed before production.
• Breaking test: sample frequency, test-piece preparation and minimum breaking load to be agreed in the inspection and test plan.
• Documentation: material certificate, dimensional report, proof-test record, breaking-test report, coating record and maker certificate as ordered.

Surface Protection & Marine Service

• Black coating is suitable as a basic protective finish where regular inspection and maintenance are expected.
• Conventional or hot-dip galvanizing can improve corrosion protection, but coating thickness can affect calibrated link geometry and pocket-wheel fit.
• For higher-strength or heat-treated chain, the galvanizing process and post-treatment inspection should be approved for the selected steel and manufacturing route.
• Contact surfaces should remain free from heavy paint build-up, zinc runs, burrs and other deposits that can disturb wheel engagement.
• Packing should prevent link-to-link impact, salt contamination and coating damage during transport and storage.

How the Chain Works in a Hatch Cover System

Hydraulic or electric drive rotates the chain wheel → Chain links engage the wheel pockets → Tension is transmitted through the connected chain run → The hatch panel moves along its rails or rolling path → Guides and tensioners control alignment → The panel reaches the open or closed position → Separate lifting, sealing and cleating systems secure the hatch

Installation, Commissioning & Maintenance

• Inspect chain wheels, guides, tensioners, attachment points and drive alignment before installing the replacement chain; worn drive components can damage a new chain.
• Install the chain with the specified link orientation, total link count, end fittings and initial tension.
• For paired drives, verify synchronized movement and equalized chain tension through the complete opening and closing cycle.
• After commissioning, check wheel seating, abnormal noise, impact, local polishing, chain twist, tension variation and end-connection security.
• Record the replacement date, chain identification, measured dimensions and test documentation in the vessel’s hatch cover maintenance records.

Selection & Inquiry Guide

Step 1: Provide vessel name, IMO number if available, hatch number, hatch cover maker, equipment type and TTS / MacGregor serial or drawing number.

Step 2: Confirm chain size and variant, bar diameter, pitch / inside length, width definition, weld position, link orientation and an unworn sample or dimensioned photo.

Step 3: Provide chain-wheel pocket dimensions, total link count, cut length, matched-pair requirement, joining links, end links, shackles and tensioner details.

Step 4: Confirm operating pull, proof load, breaking load, drive torque, panel travel, operating speed and any shock or emergency operating condition.

Step 5: Confirm steel grade, welding and heat-treatment requirements, proof and breaking tests, NDT, traceability, marking and acceptance criteria.

Step 6: Confirm finish, quantity, spare length, packaging, certificate scope, delivery destination and required delivery time.

Applications

Chain-driven side-rolling hatch covers | Main cargo hatch cover operating systems | Selected TTS / MacGregor legacy installations | Single-chain drives | Two-sided matched-chain drives | Ship repair and dry-docking replacement | Planned spare-chain supply

Certifications & Supply Documentation

Material certificates, dimensional inspection, proof-load testing, representative breaking-load testing, weld inspection, coating records and maker documentation can be arranged according to the agreed order scope. ISO 9001 is an organizational quality-management-system standard and should not be presented as a product-performance certificate for the chain.

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

Drawing & Photos

FAQ

Q1: Can chain diameter alone confirm compatibility with a TTS or MacGregor hatch cover?

A1: No. The same diameter can have different pitch, width, mass and end fittings. Compatibility must be checked against the equipment serial or drawing number, chain-wheel pockets, exact link geometry, total link count and terminal connections.

Q2: Is proof load the allowable operating pull or SWL?

A2: No. Proof load is an acceptance-test value and breaking load is a failure-limit value. The allowable operating pull is established by the hatch cover design, drive torque, panel resistance, dynamic effects, wear allowance and engineering safety factors.

Q3: Is this an original MacGregor spare part?

A3: Not unless the quotation expressly identifies OEM supply and includes the corresponding traceability. The standard page should describe the product as an independently manufactured compatible replacement for selected TTS / MacGregor systems, subject to drawing and sample verification.

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11–30 mm Hatch Cover Pull Chain for TTS / MacGregor Chain-Drive Systems | Welded Studless Replacement Chain Images