High-Frequency Welded Round Pipe

Release time：Round Pipe
Views： 22061
QR Code：
Published Date：2026-02-03 16:14:20

Request a Quote

Product desc

（1）Outer diameter, wall thickness and allowable deviation

Outer diameter D	Wall thickness t											Allowable deviation
mm	3	3.25	3.5	3.75	4	4.25	4.5	4.75	5	5.5	5.75	(±A，mm)
60												-
76												-
89												+0.20~-0.40
102												+0.20~-0.40
108												+0.20~-0.40
114												+0.20~-0.40
127												+0.20~-0.60
133												+0.20~-0.60
159												+0.20~-0.60

（2） Curvature

Outer Diameter (D)/mm	Curvature/(mm/m), not greater than
Outer Diameter (D)/mm	Normal Precision (PS.A)	Higher precision (PS.B)	High Precision (PS.C)
>16	1.5	1.0	0.5

（3）Out-of-roundness

The out-of-roundness of the steel pipe (the difference between the measured maximum outer diameter and the minimum outer diameter of the same cross-section) shall comply with the following provisions:

1、For the steel pipes used in the idlers of belt conveyors, the deviation should not exceed 50% of the allowable deviation of the outer diameter;

2、For other steel pipes, when the outer diameter is not greater than 152mm, it shall not exceed 75% of the allowable deviation of the outer diameter; when the outer diameter is greater than 152mm, it shall not exceed the allowable deviation of the outer diameter.

（4） Weld height

1. The burrs on the external weld of the steel pipe shall be removed and made smooth.

2. Steel pipes used for idlers of belt conveyors shall be delivered with internal burrs removed. At the request of the buyer, other steel pipes with an outer diameter greater than 25mm may be delivered with internal burrs removed.

3. When steel pipes are delivered with internal burrs removed, the height of the internal weld burrs shall comply with the provisions in the table, and the remaining wall thickness of the steel pipe after internal burr removal shall not be less than the minimum allowable wall thickness. If the accuracy grade of the steel pipe is not specified in the contract, it shall be implemented according to ordinary accuracy. At the request of the buyer, through negotiation between the supplier and the buyer and specified in the contract, steel pipes with internal burr heights beyond those in the table can be supplied.

Ordinary precision

Higher precision

High precision

+0.5

-0.20

*0.50

-0.05

+0.20

-0.05

（5）Weight

1. Steel pipes are delivered by theoretical weight, and can also be delivered by actual weight.

2. The theoretical weight per unit length of non-galvanized steel pipes is calculated according to formula (1) (the density of steel is 7.85kg/dm³)：

（1）W=0.0246615(D-t)t In the formula:

W——the theoretical weight per meter of the steel pipe, in kilograms per meter (kg/m);

D——the nominal outer diameter of the steel pipe, in millimeters (mm);

t——the nominal wall thickness of the steel pipe, in millimeters (mm).

（2）W' = cW where:

W' —— The theoretical weight per meter of the galvanized steel pipe, in kilograms per meter (kg/m);

C —— The weight increase coefficient of the galvanized steel pipe compared to the original pipe, see the table;

W —— The theoretical weight per meter of the steel pipe before galvanizing, in kilograms per meter (kg/m).

Wall thickness t/mm		1.2	1.4	1.5	1.6	1.8	2.0	2.2	2.5	2.8	3.0	3.2	3.5	3.8
Coefficientc	A	1.106	1.091	1.085	1.080	1.071	1.064	1.058	1.051	1.045	1.042	1.040	1.036	1.034
	B	1.085	1.073	1.068	1.064	1.057	1.051	1.046	1.041	1.036	1.034	1.032	1.029	1.027
	C	1.064	1.055	1.051	1.048	1.042	1.038	4.035	1.031	1.027	1.025	1.024	1.022	1.020
Wall thickness t/mm		4.0	4.2	4.5	4.8	5.0	5.4	5.6	6.0	6.5	7.0	8.0	9.0	10.0
Coefficientc	A	1.032	1.030	1.028	1.027	1.025	1.024	1.023	1.021	1.020	1.018	1.016	1.014	1.013
	B	1.025	1.024	1.023	1.021	1.020	1.019	1.018	1.017	1.016	1.015	1.013	1.011	1.010
	C	1.019	1.018	1.017	1.016	1.015	1.014	1.014	1.013	1.012	1.011	1.010	1.008	1.008
Wall thickness t/mm		11.0	12.0	12.7	13.0	14.2	16.0	17.5	20.0	-
Coefficientc	A	1.012	1.011	1.010	1.010	1.009	1.008	1.007	1.006
	B	1.009	1.008	1.008	1.008	1.007	1.006	1.006	1.005
	C	1.007	1.006	1.006	1.006	1.005	1.005	1.004	1.004

Note 1: For galvanized steel pipes with wall thicknesses outside the scope specified in this table, their weight coefficients shall be determined through negotiation between the supplier and the buyer.

Note 2: A, B, and C are the weight grades of the galvanized coating respectively.

（6）Technical Requirements

1. Material and Composition: High-quality carbon structural steel, carbon structural steel, low-alloy high-strength structural steel and other grades are used. The composition meets the corresponding national standards. The allowable deviation of the finished product composition complies with GB/T222. Other grades can be supplied through negotiation.

2. Manufacturing and Delivery: Manufactured with hot-rolled/cold-rolled steel strips using high-frequency resistance welding. The rolling state of the steel strip can be specified; the delivery state is welded or heat-treated, and overall/weld heat treatment delivery can also be negotiated.

3. Mechanical Properties: The tensile properties (yield, tensile strength, elongation) of the base metal meet the indicators of the corresponding grade. When the yield is not obvious, alternative values can be measured; the weld needs to undergo a transverse tensile test, and specific grades need to undergo an impact test, with indicators meeting the standards.

4. Process Performance

(1) Flattening test: The weld is placed at a specified position and pressed to a specified distance without cracks. Secondary/tertiary tests for ductility and integrity can be conducted through negotiation;

(2) Bending test: For steel pipes with an outer diameter ≤ 60.3mm, this can replace the flattening test, and there shall be no cracks in the weld after bending;

(3) Flaring test: Conducted as needed through negotiation, with a flaring rate of 6% and no cracks;

(4) Hydraulic test: Each steel pipe for fluid transportation shall undergo this test one by one. The test pressure is calculated according to the formula, and there shall be no leakage during a pressure holding time of ≥ 5 seconds. Ultrasonic/eddy current flaw detection can be used as an alternative, and in case of disputes, the hydraulic test shall prevail.

5. Surface quality: The inner and outer surfaces shall be free from defects such as cracks and scars. Minor defects not exceeding the negative deviation of the wall thickness are allowed; For steel pipes with an outer diameter > 219.1mm, repair welding is allowed (each pipe has ≤ 3 places, total length ≤ 300mm, and it is not allowed within 200mm of the pipe end). A hydrostatic test is required after repair welding; Repair welding is prohibited for steel pipes ≤ 219.1mm.

6. Galvanizing requirements (negotiable as needed)

(1) Hot-dip galvanizing shall be adopted, with a complete coating, free from unplated black spots/bubbles, and local rough surfaces and zinc nodules are allowed;

(2) Uniformity test (no redness after 5 times of copper sulfate immersion), weight test (divided into A/B/C three grades, minimum grade C is 300g/m²), and adhesion test (zinc coating does not peel off after bending/flattening) shall be conducted;

(3) Inspection of dimensions, performance and surface quality shall be completed before galvanizing, and special coating requirements can also be negotiated.

II. Disclaimer

1. The technical information, specifications, etc. contained in this document are all reference values and do not constitute an official guarantee, unless otherwise guaranteed.

2. Customers shall independently confirm the applicability and performance of this product according to the purpose of use, conditions of use, etc.

3. Our company shall not be liable for any damages arising from the use of this product, etc.

Note: Executable standards: GB/T 13793-2016 (straight-seam electric welded steel pipes), European standards: EN 10219 (for structural use) + EN 10305-2 (cold-drawn precision), Russian standards: GOST 10705-80 (technical) + GOST 10704-91 (dimensions)