Quality control

Quality Control and Inspection Department
DHDT Quality Control and Inspection Department consists of 7 persons. Two of them have 6 year experience of the drill pipe inspection of petroleum and natural gas industry. One of them has been working on metal material chemical and physical property test for 5 years. Another two of them have ASNT-TC-1A Standard’s NDT Level Ⅱ certificate of UT and MT. The rest two of them have received thread inspection training. They pursue excellence, pay attention to details and never allow any product with defect to be delivered to our customers.
Key processes inspection and inspection equipment

Incoming Inspection of Raw Material

DHDT has one spectrum analyzer. In addition to inspecting size and surface quality of raw material, chemical composition of two tubular products from each heat shall be analyzed.

Inspection of Upsetting

DHDT quality control engineers make strictly inspection about total length, internal and external shape, size of upsetting end during upsetting process.
DHDT quality control engineers well understand about drill pipes quality influenced by over heating during upsetting process.

Mechanical Properties Test and Microstructure Examination after Heat Treatment

DHDT has one universal tensile test machine and one Charpy v-notch impact test machine purchased from MTS. Mechanical property test of drill pipe can be performed according to API 5DP. DHDT quality control engineers have abundant experience about material metallographic structure identification. Strictly check structure of each batch. Results are helpful for improving heat treatment process.

DHDT quality control engineers make strictly random inspection for each batch of raw material preparing for next stage process.


DHDT flaw detection engineers have certificates of level UT2 and MT2 of ASNT-TC-1A standard. Upset connection area of each drill pipe is checked by ultrasonic test.
DHDT has one automatic non destructive test line with 16 channels ultrasonic and thickness measurements. 800 pieces of drill pipes can be tested one day. Test range of outer diameter varies from 42mm to 168mm. Make sure that there is no defect in the drill pipe body.

Tread Parameters Inspection

DHDT quality control engineers make test of each parameter by single parameter measurement of screw thread.
DHDT CNC operators will inspect each work piece with thread gauge and record data atier finishing processing screw thread.

Traceability of Product

DHDT establishes and follows procedures for maintaining trace ability to any applicable supplementary requirement and/or PSL requirement, as well as to drill-pipe-body heat and tool-joint heat. The procedures can trace the welds to the lot and to mechanical and inspection test results.

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