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Fuel Filler Neck — UI Group Engineering
Automotive Precision Engineering
Fuel Filler Neck

High-performance assemblies formed from STKM 11A carbon steel — precision bent, brazed, dual leak-tested and surface-treated to meet the most demanding automotive OEM requirements.

0 Process Stages
1,279 Max Length mm
2× Leak Tested
Product Overview

Engineered for Demanding Environments

Our fuel filler neck product range delivers precision-formed steel assemblies for automotive fuel systems — connecting the fuel cap housing to the tank, channelling fuel safely across the full service life of the vehicle.

"Built from STKM 11A low-carbon steel, precision-bent with CNC technology, brazed for leak-proof integrity, and dual-tested before every dispatch."

Dual Leak Testing

Tested before and after coating — zero-pinhole integrity at every stage.

CNC Precision Bending

Complex geometries formed to exact angles and radii with verified tolerances.

Automotive OEM Compliance

Manufacturing processes aligned to automotive industry quality standards.

1,279 mm
Max Cutting Length
Ø35.0 mm
Max Tube Diameter
390 MPa
Tensile Strength
2×
Leak Tests Per Unit
STKM 11A / JIS G3445
Material Grade & Standard
Low Carbon High Weldability CNC Ready
Technical Specifications

Engineering Grade Materials

Two pipe categories — each with distinct dimensional ranges and material variants, engineered for their specific role in the assembly.

Primary Component
Main Filler Neck Pipe
STKM 11A — JIS G3445 Low-Carbon Steel Tube
Cutting Length75 – 1,279 mm
Tube DiameterØ13.8 – Ø35.0 mm
Wall Thickness1.0 – 1.60 mm
Tensile Strength290 – 390 MPa
Tensile Range290–390 MPa
WeldabilitySuperior
DuctilityExcellent
Low Carbon <0.12% CNC Bending Ready Superior Weldability High Ductility Precision Formable
Secondary Component
Levelling Vent Pipe
Carbon Steel — Plain, Galvanized & Nickel-Coated
Cutting Length650 – 1,180 mm
Tube DiameterØ8.0 – Ø14.0 mm
Wall Thickness0.7 – 1.0 mm
Material Options3 Variants
Length Coverage650–1,180 mm
Corrosion ProtectionHigh
Joint IntegrityBrazed Seal
Plain Carbon Steel Galvanized Nickel-Coated Brazed Joint Leak-Proof
Material Standard

STKM 11A — The Automotive Benchmark

STKM 11A is a high-quality low-carbon steel tube governed by JIS G3445. Its typical tensile strength of 290–390 MPa delivers reliable mechanical performance while maintaining excellent ductility for complex bending and forming. Low carbon content ensures superior weldability and machinability for precision fabrication.

Dipsol Sdn. Bhd. Ulision Electroplating Sdn. Bhd. Certified Surface Partners
Carbon Content< 0.12%
Tensile Strength290–390 MPa
MachinabilityHigh
WeldabilitySuperior
DuctilityExcellent
Variants

Premium Surface Treatments

High-quality coating and plating processes delivering exceptional corrosion resistance, durability and an attractive finish — performed by certified partners to automotive standards.

Silver Finish
Bright silver plating delivering a premium metallic appearance with outstanding corrosion protection. Ideal for components requiring high reflectivity and a clean factory aesthetic throughout the product lifecycle.
Excellent corrosion resistance
Automotive OEM approved
Long-term surface durability
Metallic Grey
Sophisticated dark metallic grey coating offering a contemporary industrial aesthetic. Provides superior protection against moisture, rust and harsh chemical environments in underbody automotive applications.
Chemical & moisture resistant
Industrial grade durability
Uniform application quality
Black Painted
Premium matte-to-gloss black finish combining aesthetic refinement with superior environmental protection. Maximum UV resistance maintains consistent appearance under demanding automotive operating conditions.
UV & heat resistant
Rust & moisture protection
Premium appearance retention
Manufacturing Excellence

12-Stage Production Process

From raw steel tube to finished, tested and packaged component — every stage is monitored for dimensional accuracy, weld integrity and surface quality.

01
01
Raw Material
Steel Tube Selection & Inspection
Steel tube with correct material grade, diameter and wall thickness is selected from STKM 11A stock. Tube is inspected to ensure it is free from surface defects, dimensional irregularities and material inconsistencies before production begins.
02
02
Tube Forming
CNC Tube Bending
Tube is bent into the required shape using a CNC tube bending machine. Precise control of bend angles and radii ensures final geometry matches design specifications exactly. Each bent tube is verified for dimensional accuracy before proceeding.
03
03
End Processing
Hydraulic Tube Expansion
End of the steel tube is expanded using a hydraulic tube expansion machine. Tube diameter is increased to the required size to interface correctly with the fuel cap housing or connecting hose. Expanded end is inspected for correct dimensions and smooth surface finish.
04
04
Length Control
Precision Cutting
Steel tube is cut to required length using a tube cutting machine, according to design specifications to achieve correct dimensions. Cut ends are checked for squareness and freedom from burrs that could affect downstream processes.
05
05
End Forming
Spool End Formation
Both ends of the tube are formed using a hydraulic end-forming machine. Required shape for the fuel cap housing connection and hose connection interface is created at each tube end, providing correct geometry for downstream assembly and sealing.
06
06
Hole Making
Vent Tube Piercing
Hole is pierced in the steel tube using a piercing machine at the location specified for the vent tube connection. Made to the correct diameter and position, then inspected for size accuracy and deburred to ensure a clean edge before the next process.
07
07
Assembly
Sub-Assembly Integration
Sub-assembly parts are integrated to build and configure a finished and complete fuel filler neck through the welding process. Each weld joint is positioned and executed to design specifications, producing a structurally sound assembly ready for brazing.
08
08
Joining
Levelling Tube Brazing
Levelling tube is joined to the fuel filler neck using the brazing process. Filler metal is melted and flowed into the joint to create a strong, leak-proof connection that withstands fuel system pressures. Brazed joint is allowed to cool fully then inspected for quality and strength.
09
09
Quality Gate
Dual Leak Testing
Component undergoes two leak tests — one before and one after the coating/plating process — to verify full integrity at both stages. Tests ensure the component is free from leakage, surface pinholes and no excess water after testing, providing a zero-defect quality gate.
10
10
Surface Finishing
Protective Coating Application
Protective coating — silver, metallic grey or black — is applied to improve corrosion resistance and surface durability. Applied by certified partners Dipsol Sdn. Bhd. or Ulision Electroplating Sdn. Bhd. Cured after application; finished surface inspected for quality and uniformity.
11
11
Final Check
Final Dimensional & Visual Inspection
Completed filler neck is inspected comprehensively for dimensions, weld quality, coating condition and overall appearance. Every measurement is verified against the design specification. Compliance with all applicable quality standards is confirmed before release.
12
12
Dispatch Ready
Packing & Packaging
Finished filler neck is protected with plastic caps fitted to both open ends to prevent contamination and damage. Product is packaged carefully using appropriate protective materials to prevent mechanical damage during storage and transportation to the customer or assembly plant.
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