Rolled steel products - non-stainless steel
|Publication Date:||1 September 2021|
Scope and application
This programme is applicable for the approval of material manufacturers of:
- rolled steel products
as referred in the Society's rules and standards, and for which corrosion resistance is not specified. For a description of general requirements, conditions, procedures and documentation requirements related to the approval, please refer to DNV-CP-0346 which shall be applied in combination with this programme. For steel rolling mills that operate their own steelmaking facilities, the requirements of DNV-CP-0242 applies in addition to this programme.
This programme is applicable for the approval of manufacturers of products indicated in Table 1 as given in DNV-RU-SHIP Pt.2, and relevant parts of other applicable DNV rules and standards.
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 grade listed below
- each product category, see Table 1
- each kind of product form (plates, strips/coil, sections, bars etc.)
- particular processing route and manufacturing variables
- maximum tested thickness (t) or diameter.
Approval of one product form will not cover other product forms (example: round/flat bars will not cover sections). However, approval for one grade of steel may also cover approval of lower strength or toughness grades without additional approval testing. This is based on certain approval principles as given in App.A.
Approval is given to the following typical product categories:
- rolled structural steels:
- normal strength
- high strength
- extra high strength
- boilers and pressure vessel steels:
- carbon and carbon-manganese (C and C-Mn)
- steels for low temperature service:
- fine grained carbon-manganese
- nickel (Ni) alloy
- austenitic manganese (Mn) alloy
- bars for anchor chain cables and accessories
- round bars:
- carbon and carbon-manganese (C and C-Mn)
Approval is given to the following typical manufacturing variables in processing route:
- steelmaking process (BOC, EAF etc.) and secondary refining (LF, VD, VAD or VOD etc.)
- deoxidation (killed etc.)
- fine grain practice (singly or any combination of Al, Nb, V & Ti)
- casting method (CC or IC)
- dimensions of starting material
- reduction ratio
- condition of supply (AR, NR, N, TM or QT etc.).
When applicable, approval will be given for the following additional conditions:
- steel grades with specified through thickness properties, Z grade (Z25 or Z35). See Sec.3 [2.9]
- steel grade(s) of improved weldability, W grade(s) (example NV EW36 etc.)
- rolled round bars intended to be machined into components (as a substitute for forged bars) for which requirements reduction ratio, sampling, and acceptance criteria for mechanical properties requirements and NDE/inspection shall be according to DNV-RU-SHIP Pt.2 Ch.2 Sec.6 Steel forgings. Approval test scope is given in this approval program
- steels intended for high heat input welding ≥ 50 kJ/cm shall be specially approved. Approval is stated on the approval of manufacturer certificate using a high heat input welding notation, e.g. NV D32-W200, indicating approval of steel grade NV D32 for welding by heat input ≤ 200 kJ/cm. See Sec.3 [2.8]
- steel plates intended for cold formed plating may be specially approved for applications where cold forming with theoretical deformation exceeding the limits given in DNV-RU-SHIP Pt.3 Ch.3 Sec.1 [2.7] subject to additional testing (e.g. testing for strain aged condition etc.) for which test scope shall be agreed on case by case basis
- steel plates with prequalified CTOD properties of GCHAZ after welding. For this case, the manufacturer may apply for special approval to add suffix COD to the approved grades. Test scope and acceptance criteria for COD grades are given in DNV-CP-0348
- selected steel grades according to relevant international standards, for which approval justification and test scope shall be agreed on case by case basis.
- when steel rolling mill operates their own steel making and produce their semi-finished steel products (slabs/ingots/etc.)
- when raw materials for steel rolling mill (slabs/ingots/etc.) are not produced at the rolling mill, but the semi-finished steel products shall be procured from DNV approved steelmaker.
Where steel plates shall be repaired by welding, 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.
The manufacturer's own heat treatment facilities shall be evaluated and approved by the Society, either under this approval programme, or as approved heat-treatment workshop based on the approval programme DNV-CP-0351.
Approval requirements related to subcontracted heat treatment are specified in DNV-CP-0346.
Manufacture of specially designed rolled steel products for application in container ships, corrosion resistant steels for cargo oil tanks, structural hollow sections, rolled steel bars for offshore mooring chain and accessories, works carrying out decoiling of strip/coiled products, and rolled stainless steel products are not covered by this programme, but need separate approval according to following approval programs:
- DNV-CP-0348, where relevant
- DNV-CP-0347 (including pipes for structural applications)