IACS History File + TB

Transcription

1 IACS History File + TB Part A UR W28 Welding procedure qualification tests of steels for hull construction and marine structures Part A. Revision History Version no. Approval date Implementation date when applicable Rev.2 (Mar 2012) 26 March January 2013 Rev.1 (Nov 2006) 14 November January 2007 NEW (June 2005) 27 June January 2007 Rev.2 (Mar 2012).1 Origin for Change: Suggestion by a IACS member.2 Main Reason for Change: The objective was to modify the range of approval depending on type of welded joint for test assemblies specified in Table 3 Range of approval for type of welded joint..3 List of non-iacs Member classification societies contributing through the TC Forum and/or participating in IACS Working Group: None.4 History of Decisions Made: With regard to Table 3, it was proposed to remove D (both sides without gouging) from the range of approval of A (one side with backing) and also proposed to add A to the range of approval of D. As a result of Hull Panel discussions regarding these proposals, the Hull Panel agreed to the proposal to remove D at the 14 th Hull Panel meeting held in February However, the proposal to add A was unable to attain the 2/3 majority of Hull Panel members needed for approval because five members did not support the proposal..5 Other Resolutions Changes None.6 Dates: Original proposal: 28 December 2009 Made by: HP member Panel Approval: 15 February 2011 by: Hull Panel GPG Approval: 26 March 2012 (Ref _IGc) Page 1 of 9

2 Rev.1 (Nov 2006) See TB in Part B, Annex 2. NEW (Jun 2005) See TB in Part B, Annex 1. Page 2 of 9

3 Part B Part B. Technical Background List of Technical Background (TB) documents for UR W28: Annex 1. TB for NEW (June 2005) See separate TB document in Annex 1. Annex 2. TB for Rev.1 (November 2006) See separate TB document in Annex 2. Annex 3. TB for Rev.2 (March 2012) See separate TB document in Annex 3. Page 3 of 9

4 Part B, Annex 1 Technical Background Document UR W28 (June 2005) Welding procedure qualification tests of steels for hull construction and marine structures a) Objective/Scope The objective was to develop a new UR concerning welding procedure qualification test for hull construction, referring to the existing Rec.32. b) Source of Proposed Requirements The revised draft UR was developed referring to the existing IACS Recommendation 32 Guidelines on welding procedure qualification tests for hull construction, ISO Specification and qualification of welding procedures for metallic materials Welding procedure test- and other recognized standards. c) Points of Discussion The discussion on the following technical points had been made and achieved full agreement of the members: Scope; The requirements are applicable to the welding procedure qualification tests for steels specified in UR W7, W8, W11 and W16. Preliminary welding procedure specification and welding procedure specification; A preliminary welding procedure specification (pwps) is to be submitted prior to the tests. A pwps may be approved as a welding procedure specification, upon satisfactory completion of the test. Qualification of welding procedure (Longitudinal tensile test); The test is to be carried in case where the welding consumable is not approved by the Society. Qualification of welding procedure (Impact test); 1) Sampling position and notch location are to be developed depending on the thickness and the heat input. 2) The requirements(test temperature and required energy) for steels specified in UR W11 are to be specified for steels with thickness not more than 50mm and are to follow the Rec.32 which are based on the impact test requirements of welding consumable specified in UR W17. 3) The requirements for steels specified in UR W16 are to follow the requirements of base metals. 4) Test for cast and forged structural steels are to be carried out only in case where the tests are required for the base metals. Page 4 of 9

5 Part B, Annex 1 Range of approval; 1) Base metal The Range of approval for steel grade is to be specified with the following key concepts: - For each strength level, welding procedures are considered applicable to the same and lower toughness grades as that tested. - For each toughness grade, welding procedures are considered applicable to the same and two lower strength levels as that tested. - For high heat input processes above 50kJ/cm, welding procedure is applicable to that toughness grade tested and one strength level below. 2) Welding position Test assemblies are to be welded with the highest heat input position and the lowest heat input position, i.e. two positions are usually tested for approval of all positions, and all applicable tests are to be made. 3) Welding consumable Welding consumable having the same grade marks including all suffixes with that tested are to be included. 4) Heat input The upper limits of heat input for high heat input welding is to be stricter than normal heat input welding. 5) Type of joint The range of approval is to be specified with the concept that one side welding is superior to both side welding. Test records; The statement included in test record that the test piece was made according to the particular welding procedure is to be signed by the surveyor witnessing the test. Permsec Note: In connection with approval of new UR W28, GPG decided to delete Recommendation No.32 from the Blue Book. Submitted by WP/MW Chair 28/12/2004 Page 5 of 9

6 Part B, Annex 2 Technical Background Document UR W28 (Rev. 1 November 2006) Welding procedure qualification tests of steels for hull construction and marine structures a) Objective/Scope Prior to the implementation of UR W28 (June 2005), which was adopted by the Council on 27 June 2005, the member societies found difficulties in the implementation of the UR based on the contracted for construction date as specified therein. As unanimously agreed upon by WP/MW, Hull Panel, GPG and Council, the contents of the requirements for welding procedure qualification tests remain unchanged. Revision 1 to the UR aims to clarify the application date of the requirements. b) Source of Proposed Requirements No changes are made from W28 (June 2005) c) Points of Discussion Issues of W28 (June 2005) 1) In the footnote 1 of the UR, it specifies that the UR is to be uniformly implemented on ships contracted for construction from 1 January 2007 as well as the manufacturing of which is commenced on or after 1 January ) This means that all current welding procedures approved by the members societies in the past and being used by shipyards/manufacturers for long time, are no longer valid as the qualified welding procedures and new qualification tests are required to be performed for compliance with the UR W28. 3) There should be no point for introduction of the situation as mentioned in 2 above. Solutions by W28 (Rev. 1 October 2006) 1) In order to solve the implementation issue, the following limit statements are provided in the new paragraphs 1.3 and 1.4: 1.3 All new welding procedure qualification tests are to be carried out in accordance with this document from 1 July This document does not invalidate welding procedure qualification tests made and accepted by the Classification Society before 1 July 2007 provided the welding procedure qualification tests are considered by the Classification Society to meet the technical intent of this UR or have been qualified in accordance with the recognized standards such as ISO, EN, AWS, JIS or ASME. Page 6 of 9

7 Part B, Annex 2 2) The above new descriptions clarify the application/scope of the UR W28 without deletion of the footnotes 1 and 2 of W28 (June 2005) as approved by Council on 27 June ) The accepted welding procedures according to each Classification Society s rules are considered to meet the technical intent of this UR. d) Others A member advised of the need for them to reserve on certain technical aspects of the UR as a result of it's governance body review. Member will detail its reservations to Council as soon as possible. Submitted by Hull Panel Chair, October 2006 Permanent Secretariat Note (November 2006): - Item (d) added by GPG following their discussion. - Revised W28 approved by GPG and Council, 14 November 2006 (6183_IGd) Page 7 of 9

8 Part B, Annex 3 Technical Background Document UR W28 (Rev. 2 March 2012) Welding procedure qualification tests of steels for hull construction and marine structures 1. Objective/Scope To modify the range of approval depending on type of welded joint for test assemblies specified in Table 3 Range of approval for type of welded joint. 2. Engineering Background for Technical Basis and Rationale Qualifying a welding procedure from one side with backing implies a technique with a designated joint geometry (root face, root opening, and groove angle), a designated backing material, and a heat input to achieve a sound weld in the root against the backing whether the backing remains in place or is removed. Utilizing this same technique within the limits of the (one side) procedure variables in a weld made from both sides may or may not provide a satisfactory root weld depending on joint geometry and heat input limits of the procedure. 3. Source/Derivation of Proposed Requirements Hull Panel Member ISO Summary of Changes Intended for the Revised Resolution In Table 3, item D was removed from the range of approval for item A. 5. Points of Discussion and Decision by Voting Associated International Standards Rev. 1 of UR W28 was in line with the international standard ISO There was some concern regarding the fact that the changes made in Rev. 2 made the IACS requirements stricter than the ISO requirement. However, ISO is an international standard that is used for not only ships but also other industries, while an IACS UR is a requirement dedicated to ships. There is precedent among this UR and other URs where the requirements are stricter than their ISO equivalent. Additionally, there appears to be a contradiction among the more important welding qualification standards used in industry (ie ISO 15614, AWS D1.1, ASME IX) in this regard. Removing D from the range of approval of A Table 3 showed that, in cases where the welding procedure specifications of A were approved, C (both side welding with gouging) and D could be also included in the range of approval for the welding procedure specifications. Page 8 of 9

9 Part B, Annex 2 Regarding D, it is important not to leave any defects in the root pass for quality control of welded joints. The condition of a groove in the root pass is similar to that of B and the root pass is required to be a penetration bead. Accordingly, the welding condition is different from A. Therefore, it was suggested that it was not appropriate to include D in the range of approval of A. That suggestion was accepted by the Hull Panel. Adding A to the range of approval of both side without gouging D In addition to the above, it was also proposed to add A to the range of approval of D, since A would be technically covered by the qualifications for D if the qualification level required for D is properly achieved,. However, some Hull Panel members commented that the qualifications for the welding procedure for D should not cover the procedure for A, given that certain factors for A such as the type of backing strip, heat input, and weld gaps are different from those applicable to D. As a 2/3 majority was not achieved, the proposal was rejected. 6. Attachments, if any None Page 9 of 9