BQ690 Seamless Tube - CHS, RHS, SHS, Octagonal,Triangular

Beverly Steel is a major supplier of BQ690 high strength seamless hollow sections from world class steel mill with LR-Lloyd’s Register, ABS, BV, DNV, GL and KR certification, our major customers for BQ690 tubes are crane builders and see this site structural engineering industries. BQ690 with its high yield strength of minimum 690MPa and impact test property in longitudinal direction of test temperature -45degree C at average joules of 30 which meet the Obesity requirement for marine, oil and gas, structural tower, port equipment, military, navy, search and rescue industries and etc. Our supply range of hollow sections profile shapes are RHS, SHS, CHS, Elliptical, Half-Elliptical, Flat-Oval, Octagonal, Hexagonal and Triangular.

Nearest Equivalent Grade : S690 tube, S690 Hollow Sections

Chemical Analysis

Note that for 40 < wt ≤ 50mm chemistry should be different from what reported in “CHEMICAL ANALYSIS” table at below.

CHEMICAL ANALYSIS %
Grade	C	Mn	Si	P	S	Ni	Cu	V	Cr	Mo
BQ690	0.24	1.7	0.8	0.020	0.020	1.5	0.5	0.2	0.3	0.2

Other elements like Nb and Ti may be added in order to increase hardenability and improve mechanical properties up to a total combined of 0.10% max. Boron shall not be intentionally added. Non-specified residual elements shall not exceed 0.05% each.

CEV - Carbon Equivalent Value

The maximum CEV (Carbon Equivalent Valued) is determined, based on the cast analysis, by the following formula : CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

The CEV shall comply with valued stated in the table

MAXIMUM CEV VALUES
Grade	Wall Thickness (mm)	CEV (%) (max)
BQ690	Wt ≤ 12,5mm	0.72
	Wt > 12,5mm	0.72

Options : other calculation methods like PCM/CET may be agreed

Mechanical Properties

		Minimum Yield Strength (MPa)				Tensile Strength (MPa)			Min. Elong. Long%	Min. Elong. Transv%
Grade ↓	WT (mm) →	≤ 12	> 12 ≤ 20	> 20 ≤ 40	> 40 ≤ 50	≤ 20	> 20 ≤ 40	> 40 ≤ 50	ALL	ALL
BQ690		690		690	690	770	770	770	12	12

Impact Toughness

Impact tests shall be carried out in accordance with ENISO 148-1 for 10 X 10mm full size specimens in the longitudinal

direction at temperatures -45 degree C and -50 degree C(upon special request).

Energy values for Charpy-V notch test for each grade are indicated below :

IMPACT TEST PROPERTIES IN LONGITUDINAL DIRECTION
Grade	WT (mm)	Test temp. (ºC)	Min. Ave. Energy (J)
BQ690	ALL	-45	30

Weldability

The steel grades indicated in the specification are weldable with traditional welding procedures, given observance of the generally accepted technical rules. It is important to define a welding procedure that takes into account the following conditions :

- Thickness of the based material

- Specific heat input (specially for HAZ)

- Design requirements

- Welding method

- Welded material characteristics

Particular precautions should be taken towards crack susceptibility, which is more likely to happen with high thickness and high resistance. This phenomenon is connected mainly to the following factors :

- Chemical analysis (by means of CEV)

- The amount of diffusible hydrogen in the welded material

- Tensile stress concentrations at the real care health clinic south melbourne welded joint

Please send your valued inquiry to This email address is being protected from spambots. You need JavaScript enabled to view it.