Steel pipes and steel pipe fittings

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1 CLASS PROGRAMME Approval of manufacturers DNVGL-CP-0252 Edition May 2016 The content of this service document is the subject of intellectual property rights reserved by ("DNV GL"). The user accepts that it is prohibited by anyone else but DNV GL and/or its licensees to offer and/or perform classification, certification and/or verification services, including the issuance of certificates and/or declarations of conformity, wholly or partly, on the basis of and/or pursuant to this document whether free of charge or chargeable, without DNV GL's prior written consent. DNV GL is not responsible for the consequences arising from any use of this document by others. The electronic pdf version of this document, available free of charge from is the officially binding version.

2 FOREWORD DNV GL class programmes contain procedural and technical requirements including acceptance criteria for obtaining and retaining certificates for objects and organisations related to classification. May 2016 Any comments may be sent by to This service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document. The use of this document by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility for loss or damages resulting from any use of this document.

3 CHANGES CURRENT This is a new document. Changes - current Class programme DNVGL-CP Edition May 2016 Page 3

4 CONTENTS Changes current... 3 Contents Section 1 General Objective Scope and application Request for approval References... 7 Section 2 Documentation requirements Manufacturing summary Seamless tubes and pipes Welded tubes and pipes Fittings Heat treatment (if applicable) Welding for welded tubes, pipes and fittings (if applicable) Automatic non-destructive testing Other records, test facilities and procedures Test results and records...9 Section 3 Approval testing Test products and testing scope Testing requirements...11 Section 4 Automatic non-destructive testing General Appendix A Approval coverage of material grades and steel types General Changes historic...18 Class programme DNVGL-CP Edition May 2016 Page 4

5 SECTION 1 GENERAL 1 Objective The objective of this class programme (CP) is to provide a description for which the Society bases its approval of manufacturers intending to supply steel pipes and steel pipe fittings in accordance with RU SHIP Pt.2 or other applicable standards provided by the Society. Section 1 2 Scope and application This programme is applicable for the approval of material manufacturers of: Steel pipes, Steel pipe fittings, 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 DNVGL CP 0346 which shall be applied in combination with this programme. This programme is applicable for the approval of manufacturers of products indicated in Table 1 as per DNV GL rules and standards. Table 1 Range of approval: Application areas as per RU SHIP Pt.2 Ch.2 Sec.5 RU SHIP Pt.2 Ch.2 Sec.5 [2] RU SHIP Pt.2 Ch.2 Sec.5 [3] RU SHIP Pt.2 Ch.2 Sec.5 [4] RU SHIP Pt.2 Ch.2 Sec.5 [5] RU SHIP Pt.2 Ch.2 Sec.5 [6] Products Pipes for pressure systems Austenitic and ferritic-austenitic steel pipes Pipes for low temperature service Boiler and superheater tubes Pipe fittings Note: Manufacture of structural hollow sections is not covered by this program, but approval shall follow the programme DNVGL CP Approval for steel pipe fittings made by casting or forging shall follow the programmes DNVGL CP 0246 and DNVGL CP 0247, respectively. ---e-n-d---o-f---n-o-t-e--- 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 product type (i.e. pipes and/or fittings) manufacturing method (i.e. welded and/or seamless) the maximum dimensions (diameter, thickness) heat treatment and delivery condition for pipe fittings the approval is also limited to each manufactured type (such as tees, elbows, reducers). When applicable, specific approval will be given on the certificate for the following additional condition: Class programme DNVGL-CP Edition May 2016 Page 5

6 automated non-destructive testing in place of hydraulic testing. 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. Starting material / semi-finished steel products shall be produced at works approved by the Society: when pipe manufacturer operates their own steel making and/or rolling facilities to produce their own prematerial (plates/billets/ingots etc.), the the approval programmes DNVGL CP 0242 or DNVGL CP 0243 shall be applied in order to approve these facilities, as appropriate when pre-materials for pipe making are not produced at the pipe mill, these shall be procured from DNV GL approved steelmaker/rolling mill approved for the relevant grades. Manufacturer s own heat treatment facilities shall be evaluated and approved by the Society either under this approval program or as an approved "heat-treatment workshop" through the separate approval programme DNVGL CP Where pipes or fitting 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 DNVGL CP Where manufacturing steps are performed by a sub supplier, the sub supplier shall be correspondingly approved by the Society as relevant. Section 1 3 Request for approval When applying for AoM, the manufacturer shall indicate the material grades to be covered by the approval, including manufacturing method, dimensions, heat treatment and delivery conditions as per [3]. For this a list or table shall be provided, which shall include: type of products manufacturing method as part of manufacturing summary range of applicable product sizes (dimensions) applicable steel types heat treatment delivery conditions reference to DNV GL rules for the applicable chemical composition, mechanical properties and heat treatment (if applicable), or recognised standards given by the rules. Other standards are subject to recognition/acceptance. in case pre-material (plates/billets/ingots etc.) are delivered from other manufacturers: a list of raw material suppliers and a copy of their approval certificate. Class programme DNVGL-CP Edition May 2016 Page 6

7 4 References Table 2 List of references No. Reference Title 1 ASTM A370 Test Methods and Definitions for Mechanical Testing of Steel Products Section 1 2 ASTM E112 Standard Test Method for Determining Average Grain Size 3 ISO Determination of resistance to intergranular corrosion of stainless steels 4 ASTM G48 Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution 5 ASTM E562 Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count 6 ISO 643 Steels Micrographic determination of the apparent grain size 7 ISO 4967 Steel Determination of content of non-metallic inclusions Micrographic method using standard diagrams Class programme DNVGL-CP Edition May 2016 Page 7

8 SECTION 2 DOCUMENTATION REQUIREMENTS 1 Manufacturing summary Manufacturer shall submit information about the specific manufacturing process and related production records for products for which approval is requested. Documentation shall also include manufacturer s metallurgical specifications related the manufacturing process as described in this section. Section 2 2 Seamless tubes and pipes The following shall be submitted: procedure/specification for reheating of billets method of manufacture hot or cold finishing. 3 Welded tubes and pipes The following shall be submitted: welding process welding procedure specification cold finishing, if used. 4 Fittings The following documentation shall be submitted: for fittings made from tubes or pipes, starting material and method of forming for fittings made from plates, starting material, welding details as specified in [2.6]. 5 Heat treatment (if applicable) The following documentation shall be submitted: type of furnace and dimensions heating source sketch indicating the positions of thermocouples working zone dimension and sketch of working zone accuracy and calibration status of temperature control devices furnace uniformity test report furnace loading plan and procedure heat treatment procedures, specifying temperatures and holding times, and where applicable, information about heating and cooling rates, quenching medium and cooling medium after tempering records of heat treatment any re-heat treatment procedure to be given, if applicable method of cleaning after heat treatment. Class programme DNVGL-CP Edition May 2016 Page 8

9 6 Welding for welded tubes, pipes and fittings (if applicable) The following documentation shall be submitted, and is applicable for all welding, e.g. longitudinal pipe welds, girth seams, and pipe fitting welds: description of welding: equipment qualifications of welders and welding supervisors welding procedure specifications (WPS) the properties of production welding shall be qualified by welding procedure tests. Reports on welding procedure tests (WPQR) information about welding process if other than automatic welding processes of ERW or Plasma unless otherwise agreed with DNV GL, the scope of the welding procedure tests shall comply with RU SHIP Pt.2 Ch.4 Sec.5, and documented as described in approval of welding workshop (WWA) programme DNVGL CP Section 2 7 Automatic non-destructive testing See Sec.4. 8 Other records, test facilities and procedures The following documentation shall be submitted: visual inspection: relevant templates for recording, and records of previously performed visual inspections of same or similar products details and description of relevant in-house testing facilities and calibration details, test procedures and qualification of testing personnel NDT procedures, equipment for NDT including calibration details, and qualification of personnel for NDT information about and procedures for important manufacturing and testing routines, such as cutting and macrographic inspection of products etc. 9 Test results and records Additional requirements for reporting of test results: Sampling of test specimens: sketches, drawings and photos showing the position of test samples (incl. their dimensions) shall be submitted. Type of test specimens and their dimensions shall be reported, and if applicable reference shall be made to recognised standards. Chemical composition: a summary of the sampling practices and methods for chemical analysis is to be submitted the chemical composition shall be reported in percentage by mass the report shall give the specified limits and the measured content of all the required elements. Tensile test including elevated temperature tensile test, where relevant: yield (or proof) stress, tensile strength, elongation and reduction of area shall be reported. for elevated temperature test: yield stress (or 0.5% & 1% proof stress), tensile strength, elongation and reduction of area shall be reported. Charpy V-notch impact toughness test: Class programme DNVGL-CP Edition May 2016 Page 9

10 the heat number, test piece location and orientation, test temperature and absorbed energy (average and single values) and fracture appearance shall be reported. Tests for technological properties the type of test and result shall be reported, test results shall be documented by photos. the applied test method and test parameters shall be stated in the report. Metallographic examination: high quality photomicrographs showing the microstructure at 100x and 500x magnification shall be presented with a brief description. The magnification shall be indicated on the micrographs by a line symbol, e.g. with length of 0.5 mm or 100 µm. Arrows or letters may be used to identify features referred to in the report for ferritic-austenitic (duplex) stainless steels; the ferrite content shall be reported for the base material, weld metal and heat affected zone (HAZ) the applied etching methods for the metallographic examination shall be stated in the report. Hydrostatic testing: detailed records of testing shall be submitted. Corrosion testing (if applicable): reporting shall be in the format given in the reference test standard. Visual examination: report from visual inspection, dimensional measurements and surface condition. Non-destructive testing: detailed records of non-destructive testing with clear conclusions written by qualified personnel shall be submitted, giving the extent of testing, methods of testing, acceptance criteria, and qualification of the NDT operator. Section 2 Class programme DNVGL-CP Edition May 2016 Page 10

11 SECTION 3 APPROVAL TESTING 1 Test products and testing scope 1.1 General The test products shall be selected so that the testing will cover and qualify the full range of product types, grades, dimensions etc. for which approval is requested, see Sec.1 [3]. Section Extent of approval testing For each selected material grade and delivery condition, testing shall be carried out on at least two pipes, tubes or fittings, originating from two different heats. For each product and grade, testing is required for small, medium and big diameter/thickness. Test products shall be selected so that the total number of tested pipes/fittings will be at least six. Where two or more material grades shall be covered by the approval testing, subject to agreement with the Society the testing may be reduced to one heat per steel type per application area. 1.3 Selection and position of the test samples The products for testing shall be representative of the dimensions for which approval is requested. Test samples shall be taken out in final delivery condition and shall not be subjected to any separate heat treatment. The position of test specimens within the test samples shall be in accordance with the relevant rule requirements unless the other applicable standards/specifications have more stringent requirements. For fittings the test samples shall be taken from the region preferable with the highest deformation degree from each product selected for the approval test. Unless specified in the rules sampling positions may be proposed by the manufacturer and then agreed on case by case basis. 2 Testing requirements 2.1 Chemical composition chemical composition shall be determined both by heat and by product analysis and shall comprise all the elements required by relevant DNV GL rules. The analyses shall comprise any other elements intentionally added or designated as residual elements. 2.2 Tensile testing from each test block two tensile specimens shall be tested. Class programme DNVGL-CP Edition May 2016 Page 11

12 2.3 Elevated temperature tensile testing for pipes and tubes designed for use at elevated temperature, tensile test on at least two round tensile test specimens shall be performed. Test temperature shall be 300 C, or as agreed yield stress (or 0.5% & 1% proof stress), tensile strength, elongation and reduction of area shall be reported Section Impact testing impact tests on Charpy V-notch specimens shall be made for: all steel grades without specified impact toughness requirements: for products with wall thickness 10 mm all steel grades with specified impact toughness requirements and grades for sub-zero service temperature: for products with wall thickness 6 mm transverse impact specimens shall be used when outside diameter 200 mm, longitudinal specimens may be used for outside diameter is < 200 mm for sub-size specimens, the width of the specimen shall be 7.5 mm or 5 mm, whichever is larger and possible to prepare, and the actual measured energy shall be reported (without conversion to normal specimen) at least three sets of Charpy V-notch specimens shall be tested tests shall be tested at temperatures +20 C, 0 C, 20 C, and lower temperatures when required by the applicable standard for approval of grades for low temperature applications, tests shall be carried out at the lowermost temperature for which approval is requested (will be specified on approval certificate) the impact toughness requirements shall fulfil the corresponding DNV GL rule requirements at and above the specified test temperature. Grades without specified impact toughness requirements shall obtain minimum 27 J at +20 C, unless otherwise agreed. 2.5 Tests for technological properties flattening test, drift expanding test, ring expanding test or ring tensile test in accordance with steel grade and pipe/fitting dimension shall be performed as explained in Table 1. Specimens shall be taken from each end and in the middle of each test pipe, and from the region preferably with the highest deformation degree of each test fitting, respectively where ring specimens of welded pipes are subject to ring flattening test, the weld shall be set at 90 to the direction of the compressive load in the ring expanding test, the change in the diameter of the specimen expanded to the point of fracture shall at least equal the percentages shown in Table 2, depending on the material when the ring tensile test is applied to specimens of welded pipes, the weld shall be set at 90 to the direction of the tensile load in the drift expanding test applied to austenitic steel pipes a 20% expansion shall be achieved. Where pipes are made of other steels, the requirements of the other relevant standards shall be achieved in case of welded pipes/fittings the testing scope is to be supplemented as follows: Flattening tests and ring tensile tests are to be performed alternately with weld position in 9 and 12 o clock position. For pipe/ fitting diameter above 200 mm weld transverse bend test is to be performed with the outer and inner side of the weld in tension Class programme DNVGL-CP Edition May 2016 Page 12

13 in case of welded pipes/fittings the testing scope is to be supplemented as follows: Flattening tests and ring tensile tests are to be performed alternately with weld position in 9 and 12 o clock position. For pipe/ fitting diameter above 200 mm weld transverse bend test is to be performed with the outer and inner side of the weld in tension. Table 1 Applicable tests based on outside diameter and nominal wall thickness Outside diameter of pipe, D (mm) Nominal wall thickness, t (mm) t < 2 2 t t 40 Section 3 D 21.3 ring flattening test 1, 3) ring flattening test 1, 3) < D 146 ring flattening test 1, 3) ring expanding test 1, 3) ring flattening test 1,3) D > ring tensile test 2) ring tensile test 2) 1) the drift expanding test may also be applied to welded pipes 2) instead of the ring tensile test, the flattening test is applied to pipes with bores of 100 mm 3) the drift expanding test is applied to seamless and welded pipes in compliance with EN and -2 respectively Table 2 Minimum expansion ratio for change in the diameter in ring expanding test Minimum expansion (%) for ID/OD ratios of Pipe material ID/OD < ID/OD < ID/OD < ID/OD < ID/OD 0.6 ID/OD 0.5 C- and C-Mn-steels Mo-, CrMo- and Ni-steels Austenitic steels Metallographic examination one set shall be taken near the surface and one set at the mid-wall thickness of the test block for welded products, a macro section in way of the weld shall be presented in case pipe mill produce their own pre-material, sulphur prints are required for ferritic-austenitic (duplex) stainless steels, the ferrite content shall be determined in accordance with ASTM E562 or an equivalent standard. The content shall be within 35 to 55% for the base material and within 25 to 70% for the weld metal and the heat affected zone the ferrite grain size shall be reported, except for stainless steels and steels supplied in quenched and tempered condition. See ASTM E112 high quality photomicrographs showing the microstructure at 100x and 500x magnification shall be prepared with a brief description. The magnification shall be indicated on the micrographs by a line symbol, e.g. with length of 0.5 mm or 100 µm. Arrows or letters may be used to identify features referred to in the report. 2.7 Hydrostatic testing each tube and pipe shall be subjected to hydrostatic tested with a test pressure inducing a stress equal to 90 % of yield strength, also where automatic non-destructive testing is used, see Sec.4. Class programme DNVGL-CP Edition May 2016 Page 13

14 2.8 Corrosion testing (if applicable) test for resistance to corrosion shall be performed for all applicable stainless steel grades. Surface finish of the test specimens shall be representative of the surface finish of the material/product in final supply condition test sample for corrosion test shall include the area/part from fitting that experienced highest degree of deformation duplex stainless: corrosion test shall be carried out in accordance with ASTM G48 Method A or an equivalent recognised international standard the test sample position shall be at mid thickness of the thickest part of the component subject to final heat treatment or at a depth of 60 mm for 22Cr duplex and 30 mm for 25Cr duplex, respectively, whichever is less. The test temperature shall be +20 C for type 22Cr duplex and +50 C for type 25Cr duplex (+40 C for welds), respectively. The exposure time shall be 24 hours no pitting on specimen (plate) surfaces is allowed when viewed at 20x magnification. The specimen mass loss shall be less than 4.0 g/m 2 austenitic stainless: at least two specimens (preferably on material from tensile test specimens) shall be subjected to intercrystalline corrosion test in accordance with ISO or another recognized international standard the bent specimens shall be free from cracks indicating the presence of intergranular attack. Section Visual examination visual examination shall be conducted and recorded according to the relevant rule requirements the surfaces shall be adequately prepared for inspection the surfaces shall not be hammered, peened or treated in any way which may obscure discontinuities examination shall be done for all applicable sides and areas, and manufacturer shall ensure that lifting devices for handling and turning of the products are available when relevant visual examination shall include internal surfaces measurements shall be made on all applicable dimensions manufacturer shall present representative products used for approval purpose and including reports for visual inspection, dimensional measurements and surface condition Non-destructive testing each product shall be tested in accordance with the requirements of DNV GL rules inspection shall be done for all applicable sides and areas, and manufacturer shall ensure that lifting devices for handling and turning of the product are available for electric resistance or induction welded products, the weld shall be non-destructive tested according to one of the test methods of ISO 9303, ISO 9304, ISO 9402 and ISO 9764 with an acceptance level L4, or equivalent for submerged arc welded products, the weld shall be ultrasonic tested according to ISO 9765 with acceptance level L4, or equivalent. Alternatively the weld shall be subjected to a radiographic test method Class programme DNVGL-CP Edition May 2016 Page 14

15 detailed records of non-destructive testing with clear conclusions written by qualified personnel shall be prepared, giving the extent of testing, methods of testing, acceptance criteria, and qualification of NDT personnel MT (magnetic particle test) shall be carried out for ferritic steels. PT (liquid penetrant test) shall be applied for austenitic and duplex steels ultrasonic testing (UT): where required by the rules UT shall be carried out for automatic NDT of longitudinal welds, see Sec.4. Section Additional testing for welded fittings in case of welded pipe fittings the testing scope is to be supplemented as follows: tensile tests longitudinal including the weld, or transverse over the weld notch bar impact tests transverse with notch position in centre of weld and on the fusion line/heat affected zone microstructure photographs of weld centre and heat affected zone chemical composition of weld metal (fusion welded pipes only) high temperature test of weld metal (fusion welded pipes only), where relevant macro section with three hardness testing lines across the weld area (photographs with a magnification of 2:1 shall be prepared) non-destructive tests of the weld by ultrasonic and/or radiographic method Automatic non-destructive testing The manufacturer shall demonstrate calibration and testing to the surveyor. See also Sec Other tests (if applicable) in case other tests, e.g. corrosion tests, hardness tests, etc. are required by the referred standard, the test results shall be submitted. Class programme DNVGL-CP Edition May 2016 Page 15

16 SECTION 4 AUTOMATIC NON-DESTRUCTIVE TESTING 1 General where automatic non-destructive testing is used, the manufacturer is required to have online equipment for testing of the whole length of the tubes/pipes and submit the following information: general description of test method including reference to standards or specifications type of equipment and capacity, i.e. tube dimension range (wall thickness and outside diameter) calibration of equipment to establish a minimum sensitivity level for rejection, including information on dimension and position of artificial defects in standard test tubes sensitivity toward internal and external discontinuities frequency of calibration orientation of discontinuities capable of detection description or procedure for disposition of material with indications exceeding the acceptance criteria description or procedure for disposition of untested length at tube ends. Section 4 Class programme DNVGL-CP Edition May 2016 Page 16

17 APPENDIX A APPROVAL COVERAGE OF MATERIAL GRADES AND STEEL TYPES 1 General RU SHIP Pt.2 Ch.2 Sec.5 Steel types/ material grades Approval coverage for C and CMn grades: always on condition that deoxidation practice and chemical composition are similar and KV requirements are not higher for all groups: refers to grades indicated in / permitted by the DNV GL rules Appendix A Sec.5 [2] Sec.5 [3] Sec.5 [4] Sec.5 [5] C and CMn group CrNi group CrNi grades X5CrNi18-10, , TP 304 CrNiMo group Austenitic-ferritic grades C and CMn group Ni group C and CMn group Mo and CrMo group One grade tested will cover entire group, but only the grades with lower specified yield strength Testing of one CrNi grade covers entire CrNi group, except CrNiMo group and grades X5CrNi18-10, , TP 304 Covers only grades X5CrNi18-10, , TP 304 Testing of one CrNiMo grade covers entire CrNiMo group Testing of 25Cr duplex covers 22Cr duplex. Testing of 22Cr duplex covers only grade 22Cr one grade tested will cover entire group, but only the grades with lower specified yield strength covers in addition C and CMn group as per Sec.5 [2] One Ni grade tested will cover entire Ni group, but only the grades with higher design temperature (i.e. 3 ½ Ni covers 2 ¼ Ni) approval testing of any one grade will also cover all other grades with lower specified yield strength and lower toughness requirement in the same steel type group in Sec.5 [5] covers in addition C and CMn group as per Sec.5 [2] One Mo or CrMo grade tested will cover entire Mo and CrMo group, but only the grades with lower specified yield strength Sec.5 [6] All As defined above for the various steel types / material grades Class programme DNVGL-CP Edition May 2016 Page 17

18 CHANGES HISTORIC There are currently no historical changes for this document. Changes historic Class programme DNVGL-CP Edition May 2016 Page 18

19 DNV GL Driven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil and gas, and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our professionals are dedicated to helping our customers make the world safer, smarter and greener. SAFER, SMARTER, GREENER