vol6_section08

8/19/2019 Vol6_Section08

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Section 8 - Execution of Welds E, F, G 8 - 1

Section 8

Execution of Welds

A. General

1. Scope, supplementary provisions

1.1 This section contains universal rules applicable to

the performance of welding work, extending from the weld

preparation to the completion of the welded joints including

any finishing operations. For heat treatment see Section 9;

for testing of the welded joints, Sections 10 and 11.

1.2 The performance of the welding work is additionally

governed by the application-specific requirements stated

in the various Sections 12 to 16. The relevant provisionsof the respective Rules for Hull, Volume II, shall also be

complied with.

2. Welding shop requirements

2.1 All workshops wishing to carry out welding work

shall comply with the welding shop requirements stipulated

in Sections 2 (Approval), 3 (Welder's Qualification Tests)

and 4 (Welding Procedure Tests), and where necessary,

Section 10 (Non-destructive Testing of Welds).

2.2 Workshops shall maintain up-to-date records of this

compliance and shall submit them to the Surveyor at his

request. If necessary (e.g. in the case of a prolonged

interruption to the work, cf. Section 2, A.4.2 and Section.3,

E.), the Society may reinspect the workshop.

3. Materials, marking

3.1 Welding may only be performed on materials whose

identity and weldability under the given fabricating

conditions can be unequivocally established by reference

to markings, certificates, etc.

3.2 In case of doubt, the identity and weldability of the

materials shall be verified before welding commences.

4. Welding consumables and auxiliary materials

4.1 Only welding consumables and auxiliary materials

tested in accordance with Section 5, approved by the Society

and of a quality grade appropriate to the base material to

be welded may be used. The various quality grades

corresponding to the different hull structural steels shall

be as shown in Table 12.1 in Section 12.

4.2 Welding consumables and auxiliary materials for

particular materials and those intended for special welding

processes which have been approved on the basis of a(preliminary) welding procedure test may be used only for

the range of application specified in the relevant approval

certificate. Any special conditions or rules associated with

such applications shall be complied with.

4.3 Welding consumables and auxiliary materials may

only be used with the electrode diameters covered by the

tests and for the approved welding positions. The

manufacturer's instructions and recommendations for use

(e.g. the type of current and polarity used) shall be complied

with.

4.4 If necessary, welding consumables and auxiliary

materials are to be baked, prior to use, in accordance with

the manufacturer's instructions (keeping to the specified

maximum baking time) and are to be kept dry at the placeof work (in heated containers or similar).

5. Overweldable shop primers

5.1 Overweldable shop primers which are applied to

plates, sections, etc. prior to welding and are not removed

must be tested and approved in accordance with Section.6.

5.2 Welding shops shall ensure by suitable checks

(especially on the thickness of the coating) and production

tests carried out at random during the course of normal

fabrication that the quality of the welded joints is not

impaired to an unacceptable degree.

6. Manufacturing documents, company standards

6.1 Welds shall be executed in accordance with approved

drawings, welding schedules or company standards

recognized by the Society. Exceptions to this rule are subject

to the Society's consent in each individual case.

6.2 Compliance with the manufacturing documents is

the responsibility of the welding shop.

B. Weld Preparation, Assembly

1. Weld preparation

1.1 Weld preparation may be carried out by thermal

cutting or machining. Seam edges (groove faces) prepared

by thermal cutting shall be finished by machining (e.g.

grinding) if a detrimental effect on the welded joint as a

result of the cutting operation cannot be ruled out. Welding

edges of steel castings and forgings shall always be ground

as a minimum requirement; roll scale or casting skin is to

be removed.

1.2 Groove faces must be free from impurities and defects

liable to impair the quality of the welded joint, e.g. laps,

coarse grooves made by the cutting torch and slag. Prior


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Section 8 - Execution of Welds E, F, G8 - 2

to welding, the welding edges shall be inspected for defects,

e.g. cracks, inclusions, blowholes or pores, using

non-destructive testing methods if necessary.

2. Weld shapes, root openings (air gaps)

2.1 When preparing and assembling components, care

shall be taken to ensure compliance with the weld shapes

and root openings (air gaps) specified in the manufacturing

documents. With single- and double-bevel butt welds in

particular, care shall be taken to make an adequate root

opening to achieve sufficient root penetration.

2.2 The root opening shall not exceed twice the specified

gap. If the size of the gap permitted by this rule is exceeded

locally over a limited area, the gap may be reduced by

build-up welding of the side walls, subject to the consent

of the Surveyor. With fillet welds, the "a" dimension shall

be increased accordingly, or a single- or double-bevel weldshall be made if the air gap is large. Inserts and wires may

not be used as fillers.

3. Alignment of components

3.1 Components which are to be united by butt welding

are to be aligned as accurately as possible. Sections welded

to plating shall be left unwelded at the ends for this purpose.

Special attention shall be paid to the alignment of (abutting)

girders which are interrupted by transverse members. If

necessary, such alignment shall be facilitated by drilling

check holes in the transverse member which are

subsequently closed by welding.

3.2 The permissible edge alignment error depends on

the nature, importance and loading of the component

concerned and is dealt with in the various section of Sections

12 to 16. Where special loading conditions or other

requirements relevant to the application necessitate a

limitation of the edge alignment error, the allowable error

shall be stated in the manufacturing documents.

4. Tack welds and preparations for welding

4.1 Tack welds should be used as sparingly as possible

and should be made by trained personnel. Where their quality does not meet the requirements applicable to the

welded joint, they are to be carefully removed before the

permanent weld is made.

4.2 Clamping plates, temporary ties and aligning pins

shall be made from the same material as the base material

or from a material of similar composition and should not

be used more than necessary. Any damage caused during

their removal shall be competently repaired.

4.3 With mechanized welding processes or when arc

striking and end crater defects in butt welds have to be

avoided, run-in and run-off plates shall be provided incontinuation of the line of the weld.

4.4 Components must be clean and dry in the area of

the welds. Any scale, rust, cutting slag, grease, paint (except

for approved overweldable shop primers), moisture or dirt

shall be carefully removed before welding.

C. Weather Protection, Preheating

1. The areas to be welded shall be adequately protected

against climatic influences such as wind, damp and cold

and shall be preheated where necessary.

2. The need for and degree of preheating is determined

by various factors, such as chemical composition, plate

thickness, two- or three-dimensional heat dissipation,

ambient and workpiece temperatures, or heat input during

welding (energy applied per unit length of weld). Details

are given in Section 9 and various section of Sections 12

to 16.

3. Preheating shall be applied uniformly throughout

the thickness of the plate or component over a width of four

times the plate thickness, but not less than 100 mm.

Preheating may be as necessary for tack and auxiliary welds

as for fabricating welds.

D. Welding Positions, Welding Sequence

1. Welding should be performed in the optimum welding

position; positional welding is to be limited to theindispensable minimum. The welders employed on positional

welding must be qualified for the welding positions

concerned. With regard to welding in the vertical-down

position, see Section 12, H.6.

2. The welding sequence shall be chosen to allow

shrinkage to take place as freely as possible. Butt joints

in areas of plating shall invariably be fully welded prior

to attaching girders and stiffeners. The Society may require

an assembly procedure or welding sequence schedule to

be drawn up in special cases.

E. Performance of Welding

1. The welding shop shall ensure that the specified

welding parameters are adhered to and that the welding

work is expertly performed.

2. Components shall not be subjected to any appreciable

movements or vibration during welding. Parts to be

assembled while suspended from cranes or floating shall

be clamped prior to tack-welding of the joints in such a way

that no relative movement of the parts is possible.

Components which have not been fully welded and whichare to be handled or turned must have welded joints of

adequate strength.


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vol6_section08

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