ACCEPTANCE CRITERIA AND QUALITY INSPECTION METHOD OF SEAMLESS STEEL TUBE

1. Seamless steel tube chemical composition analysis:

Chemistry analysis, instrument analysis (infrared C – S device, direct reading spectrometer, zcP, etc.).

1) infrared C – S device: analysis of ferroalloy, steelmaking raw materials, the C, S in steel elements.

(2) direct reading spectrometer, the massive samples of C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi

(3) N – 0 instrument: N, O gas content analysis.

2. Seamless steel tube geometry size and appearance inspection:

1) seamless steel tube wall thickness inspection: micrometer, ultrasonic thickness gauge, at both ends of not less than eight points and record.

(2) seamless steel tube diameter, ovality check: calipers, vernier calipers, ring gauge, measure the maximum and minimum point.

(3) seamless steel tube length check: steel tape, manual, automatic length measuring.

(4) seamless steel tube bending check: straight edge, spirit level (1 m), thickness gauge, thread per meter measuring bending length, bending.

(5) seamless steel tube end groove Angle and the blunt edge check: square, card board.

3. Seamless steel tube surface quality inspection: 100%

(1) artificial visual inspection: lighting conditions, standards, experience, identification, steel pipe rotation.

(2) the NDT inspection:

A. UT ultrasonic flaw detection:

For various materials uniform surface and internal crack defects is more sensitive.

Standard: GB/T 5777-5777 levels: C5 level

B. eddy current flaw detection ET (induction)

Mainly on the dot (hole shape) is sensitive to defects. Standard: GB/T 7735-2004

Levels: B

C. magnetic particle (MT) and magnetic flux leakage inspection:

Magnetic inspection, is suitable for the ferromagnetic material surface and near surface defects detection.

Standard: GB/T 12606-12606 levels: C4 level

D. the electromagnetic ultrasonic testing:

Don’t need the coupling medium, can be applied to high temperature and high speed, the coarse surface of the steel pipeinspection.

E. penetration testing:

Fluorescence, coloring, test steel tube surface defects.