Section 2 WELDING

201. General

1. Application

(1) Welding for steel structures is to comply with these requirements and Pt 2, Ch 2 of Rules for Classification of Steel Ships.

(2) Where deemed appropriate by the Society, National Standards, internationally recognized Codes or standards considered as equivalent for those may be applied instead of requirements of this Chapter.

2. Matters to be approved

(1) Qualification of Welding Procedures

(A) Welding procedure qualification test(WPQT), in general, apply to the requirements specified in Pt 2, Ch 2, Sec 4 of Rules for Classification of Steel Ships.

(B) Procedures for the welding of all joints, including types of electrodes, edge preparations, welding techniques and proposed positions, are to be established before construction begins.

(C) Details of proposed welding procedures and sequences may be required to be submitted for

review, depending on the intended application. Special precautions, with regard to joint prep- aration, preheat, welding sequence, heat input and interpass temperature, are to be taken for welding thick sections.

(D) Ultrasonic inspection to insure the absence of injurious laminations may be required for ma- terial used where through thickness (Z-direction) properties are important.

(2) Welder

All welders to be employed

ments of Pt 2, Ch 2, Sec

equivalent.

in the construction of structure are

5 of Rules for Classification of

to be

Steel

qualified in the require-

Ships or considered as

202. Welding works and inspection

1. Plans and Specifications

(1) Submitted plans or specifications are to be in accordance with Ch 4, Sec 1 and they are to in-

dicate clearly the extent of welding for the main parts of the structure and non-destructive inspection of the weld.

(2) The welding process, filler metal and joint design are to be indicated on plans

specifications submitted for approval, which are to distinguish between manual welding.

the extent of

or in separate and automatic

(3) The Surveyor is to be informed of the planned sequences and procedures to be followed in the

erection and welding of the main structural members.

(4) In all instances, welding procedures and filler metals are to be applied which will produce sound welds that have strength and toughness comparable to that of the base material.

2. Preparation for Welding

(1) Edge Preparation and Fitting

(A) Edge preparations are to be accurate and uniform and the parts to be welded are to be fit- ted in accordance with the approved joint detail. All means adopted for correcting improper fitting are to be to the satisfaction of the Surveyor.

(B) Where excessive root openings are encountered for butt weld connections, weld build-up of the edges may be approved by the Surveyor, depending upon the location of the joint and

the welding procedures employed. Unless specially approved, such build-up of each edge,

where permitted, is not to exceed Ź/2 or 12.5 mm, whichever is less, where t is the thick- ness of the thinner member being welded.

(C) Where sections to be butt welded differ in thickness and have an offset on any side of

more than 3 mm, a suitable transition taper length is to be provided. In general, the tran- sition taper length is to be not less than three times the offset. The transition may be formed by tapering the thicker member or by specifying a weld joint design which will pro- vide the required transition.

(2) Alignment

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Means are to be provided for maintaining the members to be welded in correct position and alignment during the welding operation. In general, strongbacks or other appliances used for this purpose are to be so arranged as to allow for expansion and contraction during production welding. The removal of such items is to be carried out to the satisfaction of the Surveyor.

(3) Cleanliness

(A) All surfaces to be welded are to be free from moisture, grease, loose mill scale, excessive rust and paint. Primer coatings of ordinary thicknesses, thin coatings of linseed oil or equiv-

alent coatings may be used, provided it is demonstrated that their use has no adverse effect on the production of satisfactory welds.

(B) Slag and scale are to be removed not only from the edges to be welded but also from erich pass or layer before the deposition of subsequent passes or layers. Weld joints pre- pared by arc-air gouging may require additional preparation by grinding or chipping and wire brushing prior to welding, to minimize the possibility of excessive carbon on the surfaces.

(C) Compliance with these cleanliness requirements is of prime importance in the welding of higher strength steels, especially those which are quenched and tempered.

(4) Tack Welds

Tack welds of consistent good quality, made with the same grade of filler metal as intended for

production welding and deposited in such a manner as not to interfere with the completion of the final weld, need not be removed, provided they are found upon examination to be thor- oughly clean and free from cracks or other defects. Preheat may be necessary prior to tack welding when the materials to be joined are highly restrained. Special consideration is to be given to using the same preheat as specified in the welding procedure when tack welding high- er-strength steels, particularly those materials which are quenched and tempered. These same pre-cautions are to be followed when making any permanent welded markings.

(5) Run-on and Run-off Tabs

When used, run-on and run-off tabs are to be designed to minimize the possibility of high

stress concentrations and base-metal and weld-metal cracking.

3. Production Welding

(1) Environment

Proper precautions are to be taken to insure that all welding is done under conditions where welding site is protected against the deleterious effects of moisture, wind, and sever cold.

(2) Sequence

Welding is to be planned to progress symmetrically so that shrinkage on both sides of

structure will be equalized. The ends of frames and stiffeners should be left unattached to

the

the the

plating at the subassembly stage until connecting welds are made in the intersecting systems of

plating, framing and stiffeners at the erection stage. Welds are not to be carried across an un- welded joint or beyond an unwelded joint which terminates at the joint being welded, unless

specially approved.

(3) Preheat and Postweld Heat Treatment

(A) The use of preheat is to be considered when welding higher-strength steels, materials of thick cross section, materials subject to high restraint, and when welding is performed under high humidity conditions or when the temperature of the steel is below 0°C.

(B) The control of interpass temperature is to be specially considered when welding quenched and tempered higher-strength steels.

(C) When preheat is used, the temperature is to be in accordance with the accepted welding

procedure. Post-weld heat treatment, when specified, is to be carried out using an approved method.

(4) Low-hydrogen Electrodes or Welding Processes

Unless otherwise approved, the use of low-hydrogen electrodes or welding for welding all higher-strength steels, and may also be considered for weldments subject to high restraint. When using low-hydrogen electrodes

processes is required normal-strength steel or processes, proper

precautions are to be taken to ensure that the electrodes, fluxes and gases used for welding are clean and dry.

(5) Back Gouging

Chipping, grinding, arc-air gouging or other suitable methods are to be employed at the root or underside of the weld to obtain sound metal before applying subsequent beads for all full pene-

tration welds. When arc-air gouging is employed, the selected technique is to minimize carbon

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buildup and burning of the weld or base metal. Quenched and tempered steels are not to be flame gouged using oxy-fuel gas.

(6) Peening

The use of peening is not recommended for single-pass welds and the root or cover passes on multipass welds. Peening, when used to correct distortion or to reduce residual stresses, is to be effected immediately after depositing and cleaning each weld pass.

(7) Faring and Flame shrinking

(A) Fairing by heating or flame shrinking, and other methods of correcting distortion or de- fective workmanship in fabrication of main strength members and other members which may be subject to high stresses, are to be carried out only with the expressed approval of the Surveyor.

(B) These corrective measures are to be kept to an absolute minimum when higher-strength

quenched and tempered steels are involved, due to high local stresses and the possible deg- radation of the mechanical properties of the base material.

(8) Weld Soundness and Surface Appearance

(A) Production welds are to be sound, crack. free and reasonably free from lack of fusion or penetration, slag inclusions and porosity.

(B) The surfaces of welds are to be visually inspected and are to be regular and uniform with a

minimum amount of reinforcement and reasonably free from undercut and overlap and free from injurious arc strike.

(C) Contour grinding when required by an approved plan or specification or where deemed nec-

essary by the Surveyor is to be carried out to the satisfaction of the Surveyor.

4. Inspection of Welds

(1) Inspection of welded joints in important locations is to be partied out preferably by established non destructive test methods such as radiographic, ultrasonic, magnetic- particle or dye-penetrant inspection.

(2) An approved acceptance criterion by the Society or Guidances relating to Pt 2, Annex 2-9 of Rules for Classification of Steel Ships "Guidance for Radiographic and Ultrasonic Inspection of Hull Welds" are to be used in evaluating radiographs and ultrasonic indications(see Appendix 3-2).

(3) Radiographic or ultrasonic inspection, or both, are to be used when the overall soundness of the weld cross section is to be evaluate. Magnetic-particle or dye-penetrant inspection may be used

when investigating the outer surface of welds, as a check of intermediate weld passes such as root passes, and to check back chipped, ground or gouged joints prior to depositing sub-sequent

passes.

(4) Surface inspection of important tee or corner joints in critical locations, using an approved mag- netic-particle or dye-penetrant method, is to be conducted to the satisfaction of the Surveyor.

(5) Some steels, especially higher-strength may be susceptible to delayed cracking. When welding these materials, the final nondestructive testing is to be delayed for a suitable period to permit

detection of such defects. Weld run-on or run-off tabs may be used where practicable and these

may be sectioned for examination.

(6) The practice of taking weld plugs or samples by machining or cutting from the welded structure is not recommended and is to be used only in the absence of other suitable inspection methods. When such weld plugs or samples are removed from the welded structure, the holes or cavities thus formed are to be properly prepared and welded, using a suitable welding procedure as es- tablished for the original joint.

5. Repair Welding

(1) Defective welds and other injurious defects, as determined by visual inspection, nondestructive test methods, or leakage under hydrostatic tests, are to be excavated in way of the defects to sound metal and corrected by rewelding, using a suitable repair welding procedure to be con- sistent with the material being welded.

(2) Removal by grinding of minor surface imperfections such as scars, tack welds and arc strikes may be permitted.

(3) Special precautions, such as the use of both preheat and low-hydrogen electrodes, are to be con-

sidered when repairing welds in higher-strength steel, materials of thick cross section or materi- als subject to high restraint.

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6. Butt Welds

(1) Manual Welding Using Stick Electrodes

(A) Manual welding using stick electrodes may be employed for butt welds in members not ex- ceeding 6.5mm in thickness without beveling the abutting edges. Members exceeding 6.5 mm are to be prepared for welding using an appropriate edge preparation, root opening and root face(land) to provide for welding from one or both sides.

(B) For welds made from both sides, the root of the first side welded is to be removed to sound metal by an approved method before applying subsequent weld passes on the reverse

side.

(C) When welding is to be deposited from one side only, using ordinary welding techniques, ap- propriate backing(either permanent or temporary) is to be provided. The backing is to be fit-

ted so that spacing between the backing and the members to be joined is in accordance with established procedures. Unless specially approved otherwise, sp1ices in permanent back-

ing strips are to be welded with full penetration welds prior to making the primary weld.

(2) Submerged-arc Welding

(A) Submerged-arc welding, using wire-flux combinations for butt welds in members not exceed- ing 16 mm in thickness, may be employed without beveling the abutting edges. Members

exceeding 16 mm are normally to be prepared for welding using an appropriate edge prepa- ration, root opening and root face(land) to provide for welding from one or both sides.

(B) When it is determined that sound welds can be made without gouging, the provisions of

202. 3 (5) are not applicable. Where the metal is to be deposited from one side only, us- ing ordinary welding techniques, backing(either permanent or temporary) is to be provided and the members are to be beveled and fitted in accordance with established procedures.

(3) Gas Metal-arc and Flux Cored-arc Welding

Manual semi-automatic or machine automatic gas metal-arc welding, and flux cored-arc welding

using wire-gas combinations and associated processes, may be ordinarily employed utilizing the conditions specified in (1) except that specific joint designs may differ between processes.

(4) Electroslag and Electrogas Welding

The use of electroslag and electrogas welding processes will be subject to special consideration, depending upon the specific application and the mechanical properties of the resulting welds and heat-affected zones.

(5) Special Welding Techniques

(A) Special welding techniques employing any of the basic welding processes mentioned in (1) through (4) will be specially considered, depending upon the extent of the variation from

the generally accepted technique.

(B) Such special techniques include one side welding, narrow gap welding,

open-arc welding and consumable-nozzle electroslag welding. The use welding will also be subject to special consideration, depending upon

whether the process is used manually or automatically.

7. Fillet Welds

(1) General

tandem-arc welding.

of gas tungsten-arc the application and

(A) The sizes of fillet welds are to be indicated on detail plans or on a separate welding sched- ule and are subject to approval.

(B) The weld throat size is not to be less than 0.7 times the weld leg size. Fillet welds may be made by an approved manual or automatic technique.

(C) Where the gap between the faying than 5 mm, the weld leg size is to

surfaces of members exceeds 2 mm and is not greater be increased by the amount of the opening. Where the

gap between members is greater than 5 mm, fillet weld sizes and weld procedures are to be specially approved by the Surveyor. Completed welds are to be to his satisfaction.

(D) Special precautions such as the use of preheat or low-hydrogen electrodes or low hydrogen

welding processes may be required Where small fillets are used to attach heavy members or

sections. When heavy sections are attached be re-quired to be modified.

(2) Tee Connections

Except where otherwise indicated under (1) the be determined by the lesser thickness member

to relatively light members, the weld size may

fillet weld requirement for tee connections is to being joined. Where only the webs of girders,

beams or stiffeners are to be attached, it is recommended that the unattached face plates or

flanges be cut back. Except for girders of thickness greater than 25 mm, reduction in fillet weld

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sizes may be specially approved in accordance with either (A) or (B) specified below. However, in no case is the reduced leg size to be less than 5 mm.

(A) Where quality control facilitates working to a gap between members being attached of 1 mm

or less, a reduction in fillet weld leg size of 0.5 mm may be permitted provided that the re- duced leg size is not less than 8 mm.

(B) Where automatic double continuous fillet welding is used and qualify control facilitates

working to a gap between members being attached of 1 mm or less, a reduction in fillet weld leg size of 1.5 mm may be permitted provided that the penetration at the root is at least 1.5 mm into the members being attached and the reduced leg size is not less than 5 mm.

(3) Lapped Joints

Lapped joints are generally not to have overlaps of less width than twice the thinner plate

thickness plus 25 mm. Both edges of an overlapped joint are to have continuous fillet welds in accordance with (1) or (4).

(4) Overlapped End Connections

Overlapped end connections of structural members which are considered to be effective in the overall strength of the unit are to have continuous fillet welds on both edges equal in leg size to the thickness of the thinner of the two members joined. All other over-lapped end con- nections are to have continuous fillet welds on each edge of leg sizes such that the sum of the two is not less than 1.5 times the thickness of the thinner member.

(5) Overlapped Seams

Unless specially approved, overlapped seams are to have continuous welds on both edges of the sizes required by the approved plans and are to be in accordance with the applicable provisions of (1).

(6) Plug Welds or Slot Welds

(A) Plug welds or slot welds may be specially approved for particular applications.

(B) Where used in the body of doublers and similar locations, such welds may be generally spaced about 300 mm between centers in both directions.

(C) Slot welds generally should not be filled with weld metal. For plate thicknesses up to 13

mm, fillet sizes are to be equal to plate thickness but not greater than 9.5 mm

nesses over 13 mm to 25 mm fillet sizes are to be 16 mm maximum.

8. Full Penetration Corner or Tee Joints

Measures taken to achieve full penetration corner or tee joints, where specified, are to

for thick-

be to the

satisfaction of the attending Surveyor. Ultrasonic inspection of the member in way of the con-

nection may be required to assure the absence of injurious laminations prior to fabrication which could interfere with the attainment of a satisfactory welded joint.

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