Double Bitt Bollard with Insert Base for Ship Mooring and Towing GB/T 554 Type B

Double Bitt Bollard with Insert Base for Ship Mooring and Towing GB/T 554 Type B

Product Overview

The GB/T 554 Type B double bitt bollard is a welded steel mooring and towing fitting with an insert base arranged below the deck plating. The two vertical bitts provide separate rope turns and controlled lead positions, while the widened lower base transfers bollard loads into the vessel foundation. It is intended for ship deck locations where the design drawing specifies a recessed or inserted foundation rather than a fully deck-mounted base.

The supplied GB/T 554-2008 Type B range covers nominal diameters from 160 to 500 mm and SWL values from 49 to 451 kN. Selection must be coordinated with the vessel mooring or towing arrangement, rope lead direction, deck cut-out, local reinforcement, welding details, and the required height for decks with or without wooden covering. The material grade, low-temperature toughness, inspection scope, and final standard edition should be confirmed before production.

Quick Specifications

• Product type: Double bitt welded steel bollard with insert base → two rope-working posts with the lower foundation arranged below deck level.
• Standard and type: Supplied GB/T 554-2008 Type B data → current-edition compatibility should be confirmed when the project specifies GB/T 554-2023.
• Nominal diameter range: 160 to 500 mm → eight standard sizes for different deck layouts and specified line loads.
• SWL range: 49 to 451 kN → use the standard SWL for the selected size; do not substitute rope MBL or test load.
• Installation form: Insert base / deck-integrated foundation → deck opening, reinforcement, weld sequence, and load path require shipyard drawing confirmation.
• Deck height options: Dimensions are provided for decks without or with wooden covering → the selected H value must match the actual deck arrangement.
• Construction focus: Steel pipe and plate fabrication, smooth rope-contact edges, controlled weld geometry, and dimensional alignment of both bitts.
• Surface treatment: Sa 2.5 blasting and epoxy shop primer as reference → final coating, galvanizing, or stainless steel finish follows the project specification.

Main Technical Parameters

Main selection dimensions based on the supplied GB/T 554-2008 Type B table. Dimensions are in mm unless otherwise stated.

* The supplied D1 value for nominal diameter 355 is shown as 120 mm and requires confirmation against the official standard table or project drawing.

Selection & Inquiry Guide

Step 1: Confirm GB/T 554 Type B insert-base double bitt bollard, nominal diameter, and required SWL according to the vessel mooring or towing arrangement.

Step 2: Confirm rope type, rope diameter, expected line direction, number of turns, and whether the bollard is used mainly for mooring, towing support, or a project-specific deck operation.

Step 3: Provide the deck plan, insert-base opening, foundation arrangement, local reinforcement, weld detail, and whether the deck has wooden covering.

Step 4: Confirm material grade, minimum design temperature, ice-class or low-temperature toughness requirement, and whether stainless steel is required.

Step 5: Confirm surface treatment, final coating system, inspection scope, NDT requirement, material traceability, and classification society requirement before quotation.

Step 6: Provide quantity, vessel type, installation position, delivery destination, required delivery time, and the latest approved drawing or replacement sample information.

Structure

Twin vertical bitts | Steel pipe and plate fabricated body | Insert base below deck plating | Wide lower foundation | Smooth rope-contact edges | Deck weld interface | Local reinforcement connection | Project-specified coating

Fabrication, Welding & Installation Advantages

• The insert-base arrangement places the widened lower foundation below deck level, allowing bollard forces to be transferred into the supporting deck structure rather than being carried by the deck plate alone.
• The twin-bitt configuration provides two working posts for rope turns and line organization; the actual lead direction and permitted operating sector must follow the vessel mooring or towing plan.
• Welds and free edges in rope-contact areas can be dressed smooth, with exposed edges prepared to the specified radius, to reduce local cutting or abrasion of mooring lines.
• Fabrication jigs and dimensional checks help maintain the spacing, inclination, height, and alignment of the two bitts before final welding to the base structure.
• Foundation fit-up, deck cut-out accuracy, welding sequence, and distortion control are important because the inserted base interfaces directly with the vessel structure.
• For ice-class or low-temperature service, steel grade and impact-toughness requirements should be selected from the vessel specification and approved by the relevant classification society.
• NDT, material traceability, load verification, and class witnessing can be arranged according to the approved inspection and test plan rather than assumed as standard supply.

Custom Attributes

• Standard: GB/T 554 Type B → supplied dimensions and SWL values are based on the 2008 data set; confirm current-edition requirements before order release.
• Configuration: Double bitt with insert base → suitable where the vessel foundation is recessed below deck plating.
• Nominal Diameter: 160 / 200 / 250 / 315 / 355 / 400 / 450 / 500 mm → select together with SWL, deck arrangement, and rope lead.
• SWL: 49 / 78 / 118 / 196 / 255 / 314 / 382 / 451 kN → standard working load associated with each nominal size.
• Material: Steel pipe and plate fabrication → mild steel, stainless steel, or project-specified special steel subject to grade confirmation.
• Deck Arrangement: Without or with wooden deck → use the corresponding H dimension in the installation drawing.
• Edge Preparation: Smooth welds and radiused free edges → intended to reduce sharp local contact with mooring lines.
• Certificate Requirement: Available according to order scope → maker certificate, material certificate, class certificate, and witness inspection must be agreed before quotation.

How It Works

Mooring or towing line approaches the selected bitt → Line is turned around one or both posts according to the approved operating arrangement → Contact force is carried by the fabricated bollard body → Insert base transfers the load into the reinforced deck foundation → Welds, structure, and coating are inspected after installation

Applications

Cargo vessels | Tankers | Bulk carriers | Container ships | Tug and workboat deck fittings | Ship mooring stations | Project-specific towing support positions | Newbuilding and replacement projects

Certifications & Advantages

Certificates and inspection can be arranged according to project requirement, material traceability, approved drawing, test scope, and classification society procedure.

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

Drawing & Photos

FAQ

Q1: What is the main difference between the Type B insert-base bollard and a deck-mounted bollard?

A1: The Type B lower foundation is inserted below the deck plating. Selection therefore depends not only on SWL and nominal diameter, but also on the deck opening, foundation depth, reinforcement, welding access, and deck covering arrangement.

Q2: Can the supplied GB/T 554-2008 table be used for a project specifying GB/T 554-2023?

A2: The supplied table should be treated as the 2008 Type B reference. The current standard edition, type designation, dimensions, materials, marking, and test requirements should be checked against the official project standard before production.

Q3: What information is required before quotation?

A3: Confirm standard edition, Type B, nominal diameter, SWL, rope arrangement, material grade, minimum design temperature, deck and foundation drawing, wooden deck condition, surface treatment, certificate scope, quantity, destination, and delivery schedule.

Main Technical Parameters:

                                                              

Drawing of GB/T 554 Type B Double Bitt Bollard with Insert Base Ship Towing Equipment