DNV DNV-CP-0247 PDF

Scope and application

This programme is applicable for the approval of manufacturers of:

— Steel forgings,

as referred in the Society's rules and standards. For a description of general requirements, conditions and procedures related to the approval, please refer to DNV-CP-0346 which shall be applied in combination with this programme.

This AoM programme is applicable for the approval of manufacturers of products indicated in Table 1 as per DNV rules and standards.

Note:

Manufacture of forged chain cable accessories is not covered by this program, but need separate approval according to approval programme DNV-CP-0254.

The product(s) used for approval testing (see Sec.3) will place limitations on the range of approval. The approval will be limited to:

— each steel type group or material grade (see App.A)

— carbon and carbon-manganese (C and C-Mn) steels

— the individual alloy steels

— the individual stainless steels

— each application area, see Table 1

— forging method

— maximum forging weight

— maximum cross section and diameter

— heat treatment and delivery condition

— the reduction ratio for the products for approval testing shall be representative for the later production of the similar products.

When applicable, specific approval will be given on the certificate for the following additional conditions:

— continuous grain flow (CGF) crankshafts or crank throws; according to DNV-CG-0037

— specially approved forging process; as referred in the rules DNV-RU-SHIP Pt.4 and DNV-CG-0036

— clean steel forgings; according to DNV rules DNV-RU-SHIP Pt.2 Ch.2 Sec.6

— approved steel grades for low temperature service.

The approval is limited to the material grade for which approval tests are carried out, but certain grades may also cover other grades in the same steel type group, or the entire steel type group, as explained in App.A.

Where steel forgings are to be repaired by welding (see guidance note), or two or more items are joined by welding to form a composite item, the manufacturer's welding shop shall either be approved for welding in accordance with this programme, or be approved as welding workshop. For welding workshop approval, see DNV-CP-0352.

Guidance note:

The DNV rules give strict limitations for repair by welding on forgings. The limitations given by the rules shall always and without exception be observed. Approval for repair by welding in accordance with this programme will under no circumstances give exemptions from the relevant rule requirements.

The manufacturer’s own heat treatment facilities shall be evaluated and approved by the Society, either under this approval programme, or as an approved "heat-treatment workshop" based on the approval programme DNV-CP-0351.

Where heat treatment or case hardening is performed by a sub supplier, the sub supplier shall be approved by the Society as a heat treatment workshop in accordance with DNV-CP-0351.

Starting material/semi-finished steel products shall be produced at works approved by the Society.

For steel forges operates their own steel making and produce their semi-finished steel products (slabs/ingots/ etc.), the approval programme DNV-CP-0242 shall be used to approve these facilities.