Bolted Base Double Cross Bitt Bollard for Ship Mooring | GB/T 554 Type DL DN50

Product Specification

Bolted Base Double Cross Bitt Bollard for Ship Mooring | GB/T 554 Type DL DN50–175

Product Overview

The GB/T 554 Type DL bolted base double cross bitt bollard is a welded steel-pipe mooring bollard for vessel deck arrangements where a flat bolted base is specified. According to the supplied production clarification, the DL configuration is used for nominal diameters below DN200 and is generally selected for small vessels, workboats, barges, pontoons, and retrofit deck positions where bolted installation is required by the vessel drawing.

Compared with the Type DH deck-welded version, Type DL is defined by its flat base plate and bolted deck connection. The bollard body is fabricated from steel pipe and steel plate; the horizontal cross pipe is continuous through the double-bitt structure to support strength and force transfer. Rope-contact welds should be dressed and ground smooth to reduce rope damage, while the bolt foundation, backing plate, and deck reinforcement must be confirmed before production.

Quick Specifications

• Product type: bolted base double cross bitt bollard → flat-base deck installation when bolting is specified.
• Standard and type: GB/T 554-2008 Type DL → double cross bitt bollard structure for ship mooring equipment.
• Nominal diameter range: DN50–DN175 → used for the below-DN200 bolted version according to the supplied clarification.
• SWL range: 13–62 kN → for initial bollard selection; deck foundation and bolt arrangement require project checking.
• Construction: welded steel pipe and steel plate → fabricated from rolled plate pipe or steel pipe according to order requirement.
• Base connection: bolted flat base → bolt size, bolt grade, backing plate, and deck foundation should be confirmed before quotation.
• Rope-contact finishing: burr-free surface and smooth ground welds → helps reduce local cutting or abrasion of mooring ropes.
• Surface treatment: Sa 2.5 blasting + epoxy shop primer as reference → final paint, galvanizing, or stainless polishing follows project requirement.

Main Technical Parameters

Note: Bolt arrangement, bolt grade, deck insert / backing plate, and installation tightening requirement should be confirmed with the project drawing before production.

Selection & Inquiry Guide

Step 1: Confirm GB/T 554 Type DL and nominal diameter DN50–DN175 according to the vessel mooring arrangement.

Step 2: Confirm required SWL, rope lead direction, vessel type, and whether the deck layout requires a bolted flat-base bollard.

Step 3: Confirm bolt size, bolt quantity, bolt grade, backing plate, deck insert, and foundation structure before quotation.

Step 4: Confirm material requirement: mild steel, C-Mn steel, stainless steel, or special steel for ice-class projects if specified.

Step 5: Confirm surface treatment: shop primer, final paint system, galvanizing, mirror / satin polished stainless finish, or other specified finish.

Step 6: Confirm certificate scope before order: maker certificate, material certificate, class inspection, witness inspection, or other project requirement.

Step 7: Provide quantity, destination, required delivery time, deck drawing, and reference photos if available.

Structure

Bolted flat base | Two vertical bitts | Continuous horizontal cross pipe | Welded pipe-and-plate assembly | Smooth ground rope-contact welds | Bolt holes / foundation interface | Shop primer or specified finish

Bolted Installation, Welding & Rope-Contact Advantages

• The flat bolted base is suitable where the vessel drawing requires a removable or bolted deck foundation instead of direct deck welding.
• The continuous horizontal pipe passes through the double-bitt structure, helping strength continuity and force transfer between the two vertical bitts.
• Steel plate may be rolled into pipe and welded, or steel pipe may be used directly, depending on size, material availability, and project requirement.
• Weld beads in rope-contact areas should be ground smooth after fabrication to avoid sharp edges that may damage mooring ropes.
• The bolted base requires proper deck foundation design. Bolt grade, backing plate, hole tolerance, and tightening requirement should be confirmed by the shipyard or design office.
• Type DL is clearly differentiated from Type DH: DL uses a bolted flat base and is limited to the below-DN200 range according to the supplied clarification.

Custom Attributes

• Standard: GB/T 554-2008 → reference for Type DL bollard form, dimensions, SWL, and weight.
• Type: DL → bolted base double cross bitt configuration for deck mooring positions.
• Nominal Diameter: DN50 / DN75 / DN100 / DN125 / DN150 / DN175 → selected according to SWL, deck layout, and vessel drawing.
• SWL Range: 13–62 kN → used for bollard selection; it should not be mixed with rope MBL or lifting load terms.
• Base Form: Flat bolted base → suitable when a bolted foundation is specified for the mooring deck.
• Manufacturing Method: Welded steel pipe and steel plate → rolled plate pipe or steel pipe can be used according to project requirement.
• Rope-Contact Finish: Welds dressed and ground smooth → intended to reduce sharp local contact with mooring rope.
• Surface Treatment: Sa 2.5 blasting + epoxy shop primer as reference → final coating follows vessel painting specification or purchase order.
• Certificate Requirement: Available according to project requirement → class approval and inspection scope should be confirmed before quotation.

How It Works

Mooring rope is led to the bollard → Rope wraps around the double-cross bitt structure → Smooth pipe and dressed weld areas guide rope contact → Load is transferred through the continuous cross pipe and bolted base → Deck foundation and bolts transfer the load into the vessel structure

Applications

Small vessels | Workboats | Barges | Pontoons | Inland vessels | Harbor service craft | Retrofit mooring stations | Bolted deck foundations

Certifications & Advantages

Certificates can be arranged according to project requirement, inspection scope, material traceability, and class society approval 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 GB/T 554 Type DL and Type DH?

A1: Type DL uses a flat bolted base and is used for nominal diameters below DN200 according to the supplied clarification. Type DH uses a deck-welded base and covers the full DN50–DN300 range. The two versions should not share the same installation description or photos.

Q2: Can Type DL be used when the vessel drawing requires a welded base?

A2: Normally, a welded deck installation should use the Type DH configuration. Changing a bolted Type DL bollard into a welded arrangement requires drawing confirmation, foundation review, and welding detail approval.

Q3: What information is needed before quotation for Type DL?

A3: Confirm nominal diameter, SWL, bolt arrangement, deck foundation, material, surface treatment, quantity, certificate requirement, delivery destination, required delivery time, and deck drawing or reference photos.