Section 2 Welding

2.1.1 The plans to be submitted for approval are to indicate clearly details of the welded connections of main structural members, including the type and size of welds. This requirement includes welded connections to steel castings.

The information to be submitted should include the following:

1. Whether weld sizes given are throat thicknesses or leg lengths.

2. Grades and thicknesses of materials to be welded.

3. Location, types of joints and angles of abutting members.

4. Reference to welding procedures to be used.

5. Sequence of welding of assemblies and joining up of assemblies.

2.1.2 Unless otherwise indicated, all welding is to be in accordance with the requirements of Ch 13 Requirements for Welded Construction of the Rules for Materials.

2.2.1 The throat thickness of fillet welds is to be determined from:

Throat thickness = t _p × weld factor ×

see also Figure 10.2.1 Weld dimensions and types

Weld factors are given in Table 10.2.1 Weld factors, Table 10.2.3 Connections of primary structure and Table 10.2.4 Secondary member end connection welds.

Figure 10.2.1 Weld dimensions and types

2.2.2 Where double continuous fillet welding is proposed, the throat thickness is to be determined taking equal to 1,0.

2.2.3 The leg length of the weld is to be not less than times the specified throat thickness.

2.2.4 The plate thickness, t _p, to be used in the above calculation is generally to be that of the thinner of the two parts being joined. Where the difference in thickness is considerable, the size of fillet will be considered.

2.2.5 Where the thickness of the abutting member of the connection (e.g. the web of a stiffener) is greater than 15 mm and exceeds the thickness of the table member (e.g. plating), the welding is to be double continuous and the throat thickness of the weld is to be not less than the greatest of the following:

1. 0,21 x thickness of the table member. The table member thickness used need not exceed 25mm.

2. 0,21 (0,27 in tanks) x half the thickness of the abutting member.

3. As required by Table 10.2.2 Throat thickness limits.

2.2.6 Except as permitted by Pt 3, Ch 10, 2.2 Fillet welds 2.2.5, the throat thickness of the weld is not to be outside the limits specified in Table 10.2.2 Throat thickness limits.

2.2.7 Double continuous fillet welding is to be adopted in the following locations, and may be used elsewhere if desired:

1. Boundaries of weathertight decks and erections, including hatch coamings, companionways and other openings.

2. Boundaries of tanks and watertight compartments.

3. All fillet welds where higher strength steel is used and the global hull girder stress in way of the fillet weld exceeds 175 N/mm².

4. All structure in the after peak and the after peak bulkhead stiffeners.

5. All welding inside tanks intended for chemicals or edible liquid cargoes.

6. All lap welds in tanks.

7. Primary and secondary members to bottom shell in the 0,3L forward.

8. Primary and secondary members to plating in way of end connections, and end brackets to plating in the case of lap connections.

9. Where Pt 3, Ch 10, 2.2 Fillet welds 2.2.5 applies.

10. All water ballast tanks.

11. Other connections or attachments, where considered necessary, and in particular the attachment of minor fittings to higher tensile steel plating.

2.2.8 Where intermittent welding is used, the welding is to be made double continuous in way of brackets, lugs and scallops and at the orthogonal connections with other members.

2.2.9 As an alternative to intermittent welding, single sided welding may be used. Only mechanised single sided welding is acceptable although manual single sided welding may be used at non-critical locations e.g. deck house stiffeners. Where single sided welding is used, the welding is to be made double continuous in way of brackets, lugs and scallops and at the orthogonal connections with other members.

2.2.10 Where structural members pass through the boundary of a tank, and leakage into the adjacent space could be hazardous or undesirable, full penetration welding is to be adopted for the members for at least 150 mm on each side of the boundary. Alternatively a small scallop of suitable shape may be cut in the member close to the boundary outside the compartment, and carefully welded all round.

2.3.1 Weld factors for the connections of primary structure are given in Table 10.2.3 Connections of primary structure.

2.3.2 The weld connection to shell, deck or bulkhead is to take account of the material lost in the notch where longitudinals or stiffeners pass through the member. Where the width of notch exceeds 15 per cent of the stiffener spacing, the weld factor is to be multiplied by:

2.3.3 Where direct calculation procedures have been adopted, the weld factors for the 0,2 x overall length at the ends of the members will be considered in relation to the calculated loads.

2.3.4 The throat thickness limits given in Table 10.2.2 Throat thickness limits are to be complied with.

2.4.1 Welding of end connections of primary members is to be such that the area of welding is not less than the cross-sectional area of the member, and the weld factor is to be not less than 0,34 in tanks or 0,27 elsewhere.

2.4.2 The welding of secondary member end connections is to be not less than as required by Table 10.2.4 Secondary member end connection welds. Where two requirements are given the greater is to be complied with.

2.4.3 The area of weld, A _w, is to be applied to each arm of the bracket or lapped connection.

Table 10.2.4 Secondary member end connection welds

Connection	Weld area, A w, in cm2	Weld factor
(1) Stiffener welded direct to plating	0,25A s or 6,5 cm2 whichever is the greater	0,34
(2) Bracketless connection of stiffeners or stiffener lapped to bracket or bracket lapped to stiffener:
(a) in dry space		0,27
(b) in tank		0,34
(c) main frame to tank side bracket in 0,15L forward	as (a) or (b)	0,34
(3) Bracket welded to face of stiffener and bracket connection to plating	—	0,34
(4) Stiffener to plating for 0,1 x span at ends, or in way of end bracket if that be greater	—	0,34
Symbols
A s = cross sectional area of the stiffener, in cm2 A w = the area of the weld, in cm2, and is calculated as total length of weld, in cm, x throat thickness, in cm Z = the section modulus, in cm2, of the stiffener on which the scantlings of the bracket are based, see Pt 3, Ch 10, 3 Secondary member end connections
Note For maximum and minimum weld fillet sizes, see Table 10.2.2 Throat thickness limits

Table 10.2.5 Weld connection of strength deck plating to sheerstrake

Item	Stringer plate thickness, mm	Weld type
1	t ≤ 15	Double continuous fillet weld with a weld factor of 0,44
2	15 < t ≤ 20	Single vee preparation to provide included angle of 50° with root R ≤ t in conjunction with a continuous fillet weld having a weld factor of 0,39; or
		Double vee preparation to provide included angles of 50° with root R ≤ t
3	t > 20	Double vee preparation to provided included angles of 50° with root R ≤ t but not to exceed 10 mm
Note 1. Welding procedure, including joint preparation, is to be specified. Procedure is to be qualified and approved for individual Builders. Note 2. See also Pt 3, Ch 10, 2.2 Fillet welds 2.2.10: Note 3. For thickness t in excess of 20 mm the stringer plate may be bevelled to achieve a reduced thickness at the weld connection. The length of the bevel is in general to be based on a taper not exceeding 1 in 3 and the reduced thickness is in general to be not less than 0,65 times the thickness of stringer plate or 20 mm, whichever is the greater. Note 4. Alternative connections will be considered.

2.4.4 Where a longitudinal strength member is cut at a primary support and the continuity of strength is provided by brackets, the area of weld is to be not less than the cross-sectional area of the member.

2.4.5 Where the secondary member passes through, and is supported by, the web of a primary member, the weld connection is to be in accordance with the following:

1. In strengthening of bottom forward region:

   Comply with the requirements of Pt 3, Ch 5, 1.5 Strengthening of bottom forward.

2. Elsewhere:

   Comply with the requirements of Pt 3, Ch 10, 5.2 Arrangements at intersections of continuous secondary and primary members.

2.4.6 The throat thickness limits given in Table 10.2.2 Throat thickness limits are to be complied with.

2.5.1 Welding plant and equipment are to be in accordance with the requirements specified in Ch 13, 1.8 Welding equipment and welding consumables of the Rules for Materials.

2.6.1 Welding consumables used and associated equipment is to be in accordance with the requirements specified in Ch 13, 1.8 Welding equipment and welding consumables of the Rules for Materials.

2.7.1 Welding procedures are to be established for the welding of all joints in accordance with the requirements specified in Ch 13, 1.9 Welding procedure and welder qualifications of the Rules for Materials.

2.7.2 All welding procedures are to be tested and qualified in accordance with the requirements of Ch 12 Welding Qualifications of the Rules for Materials and are to be approved by the Surveyor prior to construction.

2.7.3 Welders and welding operators are to be proficient in the type of work to be undertaken and are to be qualified in accordance with the requirements specified in Ch 12 Welding Qualifications of the Rules for Materials.

2.8.1 A sufficient number of skilled supervisors is to be provided to ensure an effective and systematic control at all stages of welding operations.

2.9.1 Effective arrangements are to be provided by the Shipbuilder for the inspection of finished welds to ensure that all welding has been satisfactorily completed, and provision and application of NDE shall comply with the general NDE requirements as per Ch 1, 5.1 General NDE requirements of the Rules for the Manufacture, Testing and Certification of Materials, July 2022

2.9.2 All finished welds are to be subjected to non-destructive examination by personnel designated by the Builder in accordance with the requirements specified in Ch 13, 2.12 Non-destructive examination of steel welds of the Rules for the Manufacture, Testing and Certification of Materials, July 2022, and the general NDE requirements as per Ch 1, 5.1 General NDE requirements of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

2.9.3 In addition to the requirements of Pt 3, Ch 10, 2.9 Inspection of welds 2.9.2, a number of checkpoints are to be examined by volumetric examination as detailed in Pt 3, Ch 10, 2.9 Inspection of welds 2.9.4 to Pt 3, Ch 10, 2.9 Inspection of welds 2.9.9 and all NDE shall comply with the general NDE requirements as per Ch 1, 5.1 General NDE requirements of the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

2.9.4 Typical locations and number of checkpoints to be taken are shown in Table 10.2.6 Checkpoint locations. Critical locations as identified by ShipRight FDA Procedure (see Pt 3, Ch 16 ShipRight Procedures for the Design, Construction and Lifetime Care of Ships) are also to be considered. A plan of the proposed checkpoint locations is to be submitted for approval.

2.9.5 Checkpoints are not to be identified on the ship’s structural components prior to the welding taking place. Special treatment is not to be given at these locations except critical locations as identified by ShipRight FDA Procedure.

2.9.6 For ultrasonic examination the length of each checkpoint is to be 0,5 m and for radiographic examination the length is to be a minimum of 0,3 m. At weld intersections, examination is to be in both weld directions.

2.9.7 The Builder is to provide the Surveyor with all the NDE reports of the checkpoints. These reports are to be available for the Surveyor to review within a short time after inspection, normally considered to be within 10 working days of the examination being carried out. Where welds are repaired the NDE report is to include details of examination of both the defective weld and of the re-weld.

2.9.8 Where the Surveyor notes that a checkpoint has been repaired without record of the original defect, the shipyard is to carry out additional examinations on additional lengths of weld. These lengths are to be adjacent to and on both sides of the defective checkpoint. These additional examinations are to be carried out in the presence of the Surveyor and reported in accordance with Pt 3, Ch 10, 2.9 Inspection of welds 2.9.7.

2.9.9 Where checkpoints are found to contain continuous or semi-continuous defects, additional lengths of weld adjacent to and on both sides of the defective length are to be subject to further volumetric examination. For defective welds using automatic or fully mechanised process, then additional NDE shall be extended to all areas of the same weld length. The NDE reports are to be submitted in accordance with Pt 3, Ch 10, 2.9 Inspection of welds 2.9.7.

2.9.11 For the items butt and seam welds in plating, shown in Table 10.2.6 Checkpoint locations, consideration may be given for a reduction in inspection frequency for welds where volumetric inspection and the quality assurance techniques applied indicate satisfactory quality.