Galvanized Steel Tube

 

 

 

To ensure consistent performance and compliance with international standards, galvanized steel tube (also known as GI pipe, galvanized iron pipe, zinc coated steel pipe, or hot dip galvanized steel pipe) undergoes strict inspection and quality control at every production stage—from raw material selection to final shipment.

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1. Raw Material Inspection

Before production, all steel coils or steel strips are strictly tested to ensure stable mechanical properties.

Chemical composition analysis (C, Mn, Si, S, P)

Mechanical property testing (yield strength, tensile strength, elongation)

Surface defect inspection

Compliance with ASTM, EN, JIS, or GB standards

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2. Forming & Welding Inspection

For welded galvanized steel tube (ERW type), forming and welding quality is critical.

Tube diameter and wall thickness monitoring

High-frequency welding seam inspection

Weld bead uniformity check

Non-destructive testing (NDT) when required

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3. Hot-Dip Galvanizing Quality Control

The zinc coating process is the key factor affecting corrosion resistance.

Zinc bath temperature control (≈450°C)

Zinc coating thickness test (typically 40–600 g/m²)

Adhesion strength test (bending and impact tests)

Surface appearance inspection (smooth, no bare spots or peeling)

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4. Dimensional & Tolerance Inspection

Each galvanized steel tube is measured according to strict tolerance standards.

Outer diameter (OD) inspection

Wall thickness measurement

Length control (6m / 12m or customized)

Straightness and roundness checks

ASTM / EN / JIS tolerance compliance

5. Mechanical Performance Testing

To ensure structural reliability in construction and engineering use.

Tensile strength test

Yield strength test

Flattening test

Bending test

Impact resistance test

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6. Surface Quality Inspection

Visual and technical checks ensure a uniform galvanized finish.

Zinc coating uniformity

Surface smoothness

No cracks, bubbles, or peeling

Corrosion resistance evaluation

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7. Final Inspection Before Shipment

Every batch is checked before delivery to ensure zero defect supply.

Random sampling inspection (AQL standard)

Packaging condition check

Marking & labeling verification

Quantity and specification confirmation

Third-party inspection (SGS / BV / TUV available)

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 8. Certification & Standards Compliance

Our galvanized steel tubes comply with international standards to ensure global acceptance.

ASTM A53 / ASTM A500

EN 10219 / EN 39 / BS 1387

JIS G3444

ISO 9001 Quality Management System

 

 

 

 

 

 

 

Galvanized square steel pipes feature a protective zinc coating that safeguards against corrosion. Two primary manufacturing methods exist:

1. Hot-Dip Galvanized Square Pipes:

Zinc Coating: Minimum average thickness of 30µm; customizable range 40µm - 80µm.

Steel Grades: Q195 - Q355, S195 - S355, Grade A - C.

Dimensions: Outside dimensions range from 20x20mm to 600x600mm.

Wall Thickness: 2.0mm to 10mm and above.

2. Pre-Galvanized Square & Rectangular Pipes:

Zinc Coating: Minimum average coating weight of 30g/m².

Steel Grade: Q195.

Dimensions: Smaller outside dimensions, ranging from 15x15mm to 100x100mm.

Wall Thickness: Thinner walls, from 0.5mm to 2.0mm.

Outer Diameter	Square pipe: 20*20mm~400*400mm Rectangular pipe: 20*40mm~300*500mm
Wall Thickness	Square and rectangular pipe: 0.8~20mm
Length	3-12M according to client requirement
Standard	Hollow section: ASTM A53, ASTM A123, EN 10240, EN ISO 1461, EN 10219-1/-2, GB/T 3091-2015, GB/T 8162-2018, GB/T 13793-2016, GB/T 13912-2020, JIS G 3442, and AS/NZS 4534.
Material	Gr.A, Gr.B, Gr.C, S235, S275, S355, A36, SS400, Q195, Q235, Q345
Certificate	ISO 9001:2008,SGS, BV, EU CPR , ROHS ,CE
Finish of pipe	Hot dipped galvanized with zinc 220~260g/m2; Pre-Galvanized with zinc 30~150g/m2 Painted with black/varnish lacquer; Oil on the surface to prevent rust; Bare pipe without painting:
Pipe End	Plain end/ Bevel end; Groove end; Joint with flange; Threaded on two ends, one end with coupling, one end with plastic cap
Marking	As per client requirement or mill standard Painting method: Spray white paint
Packing	OD not less than 273mm: Loose packing,piece by piece. OD less than 273mm: In hexagonal seaworthy bundles packed by steel strips. small sizes nested into big sizes.
Applications	Construction / building materials steel pipe Steel structure Scaffolding pipe Fence post steel pipe Fire protection steel pipe Greenhouse steel pipe Low pressure liquid, water, gas, oil, line pipe Irrigation pipe Handrail pipe
Techinical	ERW (high - frequency welded)
Trade Term	FOB, CFR, CIF, EXW, FCA
Payment Term	T/T, LC
Delivery Time	15-45 days (based on quantity) after receiving advanced payment by T/T or LC .
Main Market	Southeast Asia, South Asia, Middle East, Europe, Middle&South America, Africa and Oceania

 

The detailed specification of Hot dipped galvanized hollow section

 

Hot Dip Galvanized- Square and Rectangular Steel Pipe size chart
Square Hollow Section	Wall Thickness	Rectangular Hollow Section	Wall Thickness
20*20	1.5mm~2mm	20*40	1.5mm~3mm
25*25	1.5mm~2mm	30*40	1.5mm~3mm
30*30	1.5mm~2.75mm	30*50	1.5mm~3.75mm
40*40	1.5mm~3.75mm	40*60	1.5mm~3.75mm
50*50	1.5mm~3mm	40*80	1.5mm~4.75mm
60*60	2.5mm~3.75mm	50*70	1.5mm~3.75mm
80*80	1.7mm~4.75mm	50*100	1.5mm~5.75mm
100*100	1.7mm~4.75mm
120*120	2.5mm~5.75mm
150*150	2.5mm~7.75mm
200*200	2.5mm~9.75mm
If you have other specification request,please message us.

 

The detailed specification of Pre galvanized hollow section

 

Square Hollow Section (SHS)	WT (mm)	Rectangular Hollow Section (RHS)	WT (mm)
16*16	0.8-1.5	20*40	0.8-2.0
19*19	0.8-2.0	25*50	0.8-2.0
20*20	0.8-2.0	30*40	0.8-2.0
25*25	0.8-2.0	30*50	0.8-2.0
30*30	0.8-2.0	37*57	0.8-2.0
32*32	0.8-2.0	40*60	0.8-2.0
35*35	0.8-2.0	37*77	0.8-2.0
38*38	0.8-2.0	25*75	1.0-2.0
40*40	0.8-2.0	40*80	1.0-2.2
50*50	0.8-2.0	50*100	1.0-2.2
60*60	1.0-2.2	50*75	1.0-2.2
80*80	1.0-2.2	38*75	1.0-2.2
100*100	1.0-2.3	50*75	1.0-2.2

 

 

1. Hot-Dip Galvanized Round Pipes

Zinc Layer Thickness: Minimum Average Thickness 30µm (Customizable: 40µm–80µm)
Material Grades Q195–Q355, S195–S355, Grades A–C
Outer Diameter Range: 21.3mm–630mm
Wall Thickness Range: 2.0mm–16mm (Customizable: Thicker)
Typical Applications: Water/Gas Pipes, Fire Protection Systems, Building Structural Support

2. Pre-Galvanized Round Pipes

 

Zinc Layer Weight: Minimum Average Thickness 30g/m² (Typical: 20–50g/m²)
Material Grade Q195
Outer Diameter Range: 10mm–165mm
Wall Thickness Range: 0.8mm–2.5mm
Applications: Furniture Frames, Electrical Housings, Lightweight Guardrails

COMMODITY NAME	GALVANIZED ROUND SECTION WELDED STEEL PIPE/ TUBE ( GI TUBE/ GI PIPE)
SIZE RANGE	DIAMETER: 21.3MM-610MM ; THICKNESS: 1.0MM--15.0MM
MATERIAL GRADE	Q195 = S195 / A53 Grade A Q235 = S235 / A53 Grade B / A500 Grade A / STK400 / SS400 / ST42.2 Q355 = S355JR / A500 Grade B Grade C
STANDARD	ASTM A53 ( sch10; SCH40), ASTM A500, BS1387， EN39， BS1139, ISO65 GB/T3091, GB/T13793
ZINC COATING	40~200G/M2 ( OR CUSTOMIZED)
PIPE ENDS	PLAIN ENDS / BEVEL ENDS WITH PLASTIC CAPS/ THREADED BOTH ENDS WITH COUPLING AND CAPS/ GROOVED ENDS
DELIVERY TIME	7-10 days after receiving advanced payment

 

 

 

 

 

Xi'an Dongmeng Group Co., Ltd. is one of the leading galvanized steel tube manufacturers and suppliers in China. We warmly welcome you to buy or wholesale cheap galvanized steel tube in stock here from our factory. All customized products are with high quality and competitive price. For free sample, contact us now.