GB/T 3087 20 Seamless Steel Tubes for Low and Medium Pressure Boiler, 10, 20

GB/T 3087 Seamless Steel Tubes for Low and Medium Pressure Boiler

Standard: GB/T 3087
Equivalent Standards: EN 10216-1, EN 10216-2, DIN 17175, BS 3059 Part II, NF A 49-213, NBR 5594, ISO 9329-1

Material: 20
Equivalent Materials: 1020, St45.8, SA106B, 410, P265TR1 (1.0258), P265TR2 (1.0259), P265GH (1.0425), 0.25C

Chemistry Composition

C, %	Mn, %	Si, %	P, %	S, %	Cr, %	Ni, %	Cu, %
0.17-0.23	0.35-0.65	0.17-0.37	0.035 max	0.035 max	0.15 max	0.30 max	0.25 max

Mechanical Properties

Tensile Strength , MPa	Yield Strength , MPa	Elongation, %
410-550	245 min	20 min

Outside Diameter & Tolerance

Type of Steel Pipes	Allowable Deviation
Hot Rolled Steel Pipe	±1%D or ±0.5, whichever is greater
Hot Extruded Steel Pipe	±1%D or ±0.5, whichever is greater
Thermal Expansion Steel Pipe	±1%D or ±0.5, whichever is greater
Cold Drawn Steel Pipe	±0.75%D or ±0.3, whichever is greater
Cold Rolled Steel Pipe	±0.75%D or ±0.3, whichever is greater

Wall thickness & Tolerance

Type of Steel Pipes	Outside Diameter, D	S/D	Allowable Deviation
Hot Rolled Steel Pipe	≤102mm	-	±12.5%S or ±0.40mm, whichever is greater
	>102mm	≤0.05	±15%S or ±0.40mm, whichever is greater
		>0.05~0.10	±12.5%S or ±0.40mm, whichever is greater
		>0.10	+12.5%S/-10%S
Hot Extruded Steel Pipe	≤102mm	-	±12.5%S or ±0.40mm, whichever is greater
	>102mm	≤0.05	±15%S or ±0.40mm, whichever is greater
		>0.05~0.10	±12.5%S or ±0.40mm, whichever is greater
		>0.10	+12.5%S/-10%S
Thermal Expansion Steel Pipe	-		±15%S

Type of Steel Pipes	Wall Thickness, S	Allowable Deviation
Cold Drawn Steel Pipe	≤3	+15%S/-10%S or ±0.15mm, whichever is greater
Cold Drawn Steel Pipe	>3	+12.5%S/-10%S
Cold Rolled Steel Pipe	≤3	+15%S/-10%S or ±0.15mm, whichever is greater
Cold Rolled Steel Pipe	>3	+12.5%S/-10%S

Length

The typical length of the steel pipe is 4000mm~12500mm. After negotiation with clients, other lengths can be supplied.

Fixed length or multi-length is not more than 6000mm	+10/-0mm
Fixed length or multi-length is greater than 6000mm	+15/-0mm

Straightness

Steel Pipe Wall Thickness, mm	Curvature per Meter, mm/m
≤15	≤1.5
>15~30	≤2.0
>30 or D≥351	≤3.0

The full-length curvature of the steel pipe should not exceed 0.15‰ of the total length, and the full-length curvature should not be greater than 12mm.

The burrs at the end of the steel pipe should be removed.

Steel should be smelted by electric arc furnace plus external refining or oxygen blown converter plus external refining. The tube billets can be manufactured by continuous casting or hot rolling (forging). Steel ingots can also be used directly as tube billets.

GB 3087 specifies the order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of seamless steel pipes for low and medium pressure boilers. GB 3087 is suitable for manufacturing various high-quality carbon structural steel seamless steel tubes for low-pressure and medium-pressure boilers.
GB 3087规定了低中压锅炉用无缝钢管的订货内容、尺寸、外形、重量、技术要求、试验方法、检验规则、包装、标志和质量证明书。GB 3087适用于制造各种低压和中压锅炉用的优质碳素结构钢无缝钢管。

Steel pipes shall be manufactured by hot rolled, hot extruded, thermal expansion, cold drawn or cold rolled methods.
Hot rolled, hot extruded and thermal expansion steel pipes are delivered in the delivery condition of hot rolled or normalizing, the final rolling temperature of steel pipes delivered in hot rolled condition should not be lower than the phase transformation critical temperature. Cold drawn and cold rolled steel pipes shall be delivered in normalizing delivery condition.

There should be no visible cracks, folds, scars and delamination on the inner and outer surfaces of the steel pipes. These defects should be completely removed, the removed depth should not exceed the lower deviation of the wall thickness, and the actual wall thickness at the cleaned area should not be less than the minimum value allowed of the wall thickness. Other local defects not exceeding the deviation under the wall thickness are allowed to exist.

Type of inspection or test	Frequency of Testing
Chemical analysis	One sample per heat number
Tensile test	One sample on each of the two steel pipes per lot
High temperature tensile test	One sample on each of the two steel pipes per lot
Flattening test	One sample on each of the two steel pipes per lot (for steel pipes with an outside diameter D>22~400mm, and a wall thickness not greater than 10mm)
Flaring test	One sample on each of the two steel pipes per lot (for steel pipes with a wall thickness of not greater than 8mm)
Bending test	One sample on each of the two steel pipes per lot (for steel pipes with an outside diameter not greater than 22mm)
Hydrostatic test	Each pipe, dwell time is not less than 5s, can be replaced by eddy current test
Eddy current test	Each pipe
Magnetic flux leakage detection	Each pipe, can be replaced by eddy current test
Ultrasonic test	Each pipe
Macroscopic examination	One sample on each of the two steel pipes per lot
Dimension and shape	It should be measured with a measuring tool that meets accuracy requirements
Inner and outer surfaces	It should be visually inspected under sufficient lighting conditions

Lot rule

Each lot should be composed of steel pipes of the same grade, the same heat number, the same specification and the same heat treatment system (furnace). The quantity is as follows:

The outside diameter is not greater than 76mm, and the wall thickness is not greater than 3mm: 400 pieces;

Outside diameter is greater than 351mm: 50 pieces;

Other sizes: 200 pieces;

If the number of remaining steel pipes is not less than 50% of the above-mentioned rule, they should be listed as a separate lot. In case less than 50% of the above-mentioned rule, it can be merged into adjacent lot of the same grade, the same heat number, and the same specification.

U bending can be offered, also see the fin tubes.

Keyword: boiler steel pipes, GB 3087 10# 20#

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