Section 8 Welding

8.1.1 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, see Pt 2, Ch 1, 8.4 Welding of primary and secondary member end connections.

8.1.2 Unless otherwise indicated, all welding is to be in accordance with the requirements of Ch 13 Requirements for Welded Construction of the Rules for the Manufacture, Testing and Certification of Material (hereinafter referred to as the Rules for Materials).

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

Weld factors are given in Table 1.8.1 Details of various fillet weld connections.

Figure 1.8.1 Weld types

8.2.2 Where double continuous fillet welding is proposed, the throat thickness is to be determined taking equal to 1,0. The leg length of the weld is to be not less than the specified throat thickness.

8.2.3 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.

8.2.4 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;

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

3. as required by Item 3 in Table 1.8.3 Throat thickness limits.

8.2.5 Except as permitted by Pt 2, Ch 1, 8.2 Fillet welds 8.2.4, the throat thickness of the weld is not to be outside the limits specified in Table 1.8.3 Throat thickness limits.

8.2.6 Continuous 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 lap welds in tanks.

4. Primary and secondary members to bottom shell.

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

6. Where Pt 2, Ch 1, 8.2 Fillet welds 8.2.4 applies.

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

8. Fillet welds where higher tensile steel is used.

8.2.7 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.

Table 1.8.2 Weld connection of strength deck plating to sheerstrake

Item	Stringer plate thickness	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 50º with root R ≤ 1/3 t in conjunction with a continuous fillet weld having a weld factor of 0,39 or Double vee preparation to provide included angles of 50º with root R ≤ 1/3 t
3	t > 20	Double vee preparation to provide included angles of 50º with root R ≤ 1/3 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. For thickness t in excess of 30 mm, the stringer plate may be bevelled to achieve a reduced thickness at the weld connection. The width of bevel is, in general, to be not less than twice the thickness of stringer plate and the reduced thickness, in general, to be not less than 0,65 times the thickness of stringer plate or 20 mm, whichever is the greater. Note 3. Alternative connections will be considered.

8.3.1 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.

8.3.2 Where the width of notch exceeds 15 per cent of the stiffener spacing, the weld factor is to be multiplied by:

8.3.3 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.

8.3.4 The throat thickness limits given in Table 1.8.3 Throat thickness limits are to be complied with.

8.4.1 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.

8.4.2 The welding of secondary member end connections is to be not less than as required by Table 1.8.4 Primary and secondary member end connection welds. Where two requirements are given, the greater is to be complied with.

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

8.4.4 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.

8.4.5 Where the secondary member passes through, and is supported by, the web of a primary member, the weld connection is to have an area not less than 0,5 and a weld factor of 0,34 in tanks or 0,27 in dry spaces. is defined in Table 1.8.4 Primary and secondary member end connection welds.

8.4.6 The throat thickness limits given in Table 1.8.3 Throat thickness limits are to be complied with.

Table 1.8.4 Primary and 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	1,2	0,27
(b) in tank	1,4	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 weld, in cm2, and is calculated as total length of weld, in cm, x throat thickness, in cm Z = the section modulus, in cm3, of the stiffener on which the scantlings of the bracket are based
Note For maximum and minimum weld fillet sizes, see Table 1.8.3 Throat thickness limits.

8.5.1 Welding is to be conducted in accordance with the requirements specified in Ch 13,1 and 2 of the Rules for Materials

8.6.1 Welding consumables used and associated equipment are to be in accordance with the requirements specified in Ch 13,1.8 and 2.2 of the Rules for Materials.

8.7.1 Inspection of welds is to be conducted in accordance with the requirements specified in Ch 13, 1 General welding requirements and Ch 13, 2 Specific requirements for ship hull structure and machinery of the Rules for Materials.

8.7.2 The location and number of welds to be examined by non-destructive examination is to be agreed between the Builder and the Surveyor. Recommended locations and the number of non-destructive examinations are shown in Table 1.8.5 Inspection of welds

8.7.3 For docks specially designed to operate in low temperature ambient conditions such as those prevailing in Arctic areas, the extent of non-destructive examination will be specially considered.

8.7.4 For structural details, reference should be made to Pt 3, Ch 10 Welding and Structural Details of the Rules for Ships.