The electronic pdf versions of the documents found through http://www.dnv.com/ are the officially binding versions. Copyright Det Norske Veritas.

[Book] [Expand] [Collapse] [Search Forms] [Previous Section with Hits] [Next Section with Hits] [Clear Search] [Help]

Expand Search

Sec.2: Steel Pipes [Table of Contents] B: Pressure Pipes

DNV-OS-B101 Metallic Materials

[-] Ch.2: Technical Provisions
[-] Sec.2: Steel Pipes
[-] A: General Requirements

Ch.2 Sec.2
A. General Requirements

Ch.2 Sec.2
A 100   Scope

Ch.2 Sec.2 A
101   This sub-section specifies the general requirements for steel pipes to be used in the construction of piping for pressure, cargo, and process systems. Provision is made for carbon and carbon-manganese, alloy, and stainless steels. Separate requirements for steel piping fittings are given in F.

Ch.2 Sec.2 A
102   Pipes shall be in accordance with recognised standards, as given in B to E, provided that additionally supplementary requirements equivalent to specific requirements in B to E are also met. Recognition of other standards is subject to agreement.

Ch.2 Sec.2 A
103   Pipe grades selected from recognised standards shall be suitable for bending, flanging, and similar forming operations, and for welding.

Ch.2 Sec.2 A
104   Where required by the relevant design and construction parts of the DNV Offshore Standards, pipes shall comply with the requirements of Ch.1 Sec.1 and Sec.6

Ch.2 Sec.2 A
105   Where the use of material with differing requirements is proposed, particulars shall be submitted in connection with the approval of the design for which the material is proposed. As a minimum the following particulars shall be specified: manufacturing process, chemical composition, heat treatment, mechanical properties, leak tightness testing and non-destructive testing.

Ch.2 Sec.2
A 200   Manufacture

Ch.2 Sec.2 A
201   Pipes shall be manufactured as specified in B to E. The terms "hot finished" and "cold finished" apply to the condition of the pipe before it is heat treated.

Ch.2 Sec.2 A
202   When welded, an automatic non-destructive testing of the whole length of the weld is required. Such pipes are considered equivalent to seamless pipes.

Ch.2 Sec.2
A 300   Chemical composition

Ch.2 Sec.2 A
301   The chemical composition of each heat shall be determined by the steel manufacturer on a sample taken preferably during the pouring of the heat and shall be in accordance with the requirements of the relevant standard. When multiple heats are tapped into a common ladle, the ladle analysis shall apply.

Ch.2 Sec.2 A
302   Unless otherwise required by the standard, suitable grain refining elements may be used at the discretion of the manufacturer. The content of such elements shall be reported.

Ch.2 Sec.2 A
303   Elements designated as residual elements in the standard shall not be intentionally added to the steel. The content of such elements shall be reported.

Ch.2 Sec.2 A
304   Unless stricter requirements are specified in the standard, carbon and carbon-manganese steel shall conform to a carbon equivalent of 0.50% maximum as determined by the following formula:

raster

Ch.2 Sec.2
A 400   Heat treatment

Ch.2 Sec.2 A
401   The pipes shall be supplied in a condition in accordance with the requirements of the relevant standard. Unless otherwise required by the standard, hot finished or as-welded pipes need not be heat treated.

Ch.2 Sec.2
A 500   Mechanical testing

Ch.2 Sec.2 A
501   Pipes shall be sampled and subjected to testing in accordance with the requirements of the relevant standard. Unless stricter requirements are specified in the standard, the size of a test unit (batch) shall be restricted to maximum 400 pipes and as given in 502 and 503.

Ch.2 Sec.2 A
502   Where heat treatment has been carried out, a test unit shall consist of pipes of the same size, made from the same grade of steel, and the same heat treatment in a continuous furnace or heat treated in the same furnace charge in a batch furnace.

Ch.2 Sec.2 A
503   Where no heat treatment has been carried out, a test unit shall consist of pipes of the same size, made by the same method, and from the same grade of steel.

Ch.2 Sec.2 A
504   Where Charpy V-notch impact testing is required, this is applicable for wall thickness 6 mm or greater.

Ch.2 Sec.2
A 600   Leak tightness testing

Ch.2 Sec.2 A
601   Each pipe shall be subjected to a hydraulic test or an approved non-destructive test for leak tightness in accordance with the requirements of the relevant standard. Unless stricter requirements are specified in the standard, the testing shall be as given in 602.

Ch.2 Sec.2 A
602   Where hydraulic testing is carried out, the maximum test pressure need not exceed 70 bar.

Ch.2 Sec.2
A 700   Inspection

Ch.2 Sec.2 A
701   Pipes shall be subjected to visual inspection and measurements of dimensions in accordance with the requirements of the relevant standard. Unless stricter requirements are specified in the standard, the pipes shall be inspected at the same frequency as that required for mechanical testing.

Ch.2 Sec.2 A
702   The pipes shall have a workmanlike finish consistent with the method of manufacture and shall be free from external and internal defects that can be detected by visual inspection.

Ch.2 Sec.2
A 800   Repair

Ch.2 Sec.2 A
801   Defects may be removed by grinding provided that the dimensional tolerances are not exceeded. Repair by welding is not permitted except for repair to the weld seam of electric fusion welded pipe.

Ch.2 Sec.2
A 900   Identification

Ch.2 Sec.2 A
901   Pipes shall be legibly marked for identification in accordance with the requirements of the relevant standard.

Ch.2 Sec.2
A 1000   Certification

Ch.2 Sec.2 A
1001   The manufacturer shall provide the type of inspection certificate required in the relevant design and construction rules giving the following particulars for each test unit which has been accepted:
—purchaser's name, order number and vessel identification, where known
—manufacturer's name
—description of pipes and material quality
—identification marking of pipes
—heat number and chemical composition
—results of mechanical tests and technological tests
—results of leak tightness testing
—results of any supplementary and additional test requirements specified.
Sec.2: Steel Pipes [Table of Contents] B: Pressure Pipes