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CASE

2018-2

CASES OF ASME BOILER AND PRESSURE VESSEL CODE

Approval Date: August 11, 1997

See Numeric Index for expiration

and any reaffirmation dates.

Case 2018-2

Laser Welding of Lap Joints

Section VIII, Division 1

Inquiry: May laser welding of lap joints P-Nos. 8,

44, 45, and 51 materials be used under Section VIII,

Division 1?

Reply: It is the opinion of the Committee that laser

welding of lap joints P-Nos. 8, 44, 45, and 51 materials

may be used under Section VIII, Division 1 pro-

vided that:

(a) a written Welding Procedure Specification (WPS)

shall be prepared to the requirements of Section IX

and those described below. The following additionalessential variables shall apply:

(1) Joint Design

(a) an increase in the fit-up gap;

(b) a change of more than 10% in the distance

to the edge of the material;

(c) a change of more than 10% in the joint

overlap;

(d) a change in the number of layers of material;

(e) a change in the method of surface condition-

ing at the metal-to-metal interfaces.

(2) Technique

(a) the addition or deletion of beam oscillation;

(b) Procedure Qualification Requirements

(1) Qualification of the WPS shall consist of

a visual examination, six tension shear specimens, and

eight metallurgical specimens.

(2) The qualification test coupon shall be

prepared in accordance with the variables described in

the pertinent WPS and shall be of sufficient size to

provide the test specimens indicated in Fig. 1.

(3) Prior to reducing the test coupon to the

required test specimens, the weld surfaces shall be

visually examined and shall be smooth and free from

cracks, surface flash, and pits.

(4) Tension Shear Specimens and Acceptance

Criteria

(a) The tension shear specimens shall

conform to the dimensions indicated in the table of

Fig. 1. Each specimen shall be ruptured under a tensileload. The maximum load and manner of failure shall

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be recorded on the PQR. Tensile strength shall be

computed by dividing the maximum load by the least

cross-sectional area of the specimen, or by the totalcross-sectional area of the weld in a direction normal

to the load, in either case before the load is applied.

(b) Acceptance Criteria. In order to pass

the tension shear test, the requirements of Section IX,

QW-153 shall apply.

(5) Metallurgical Specimens and Criteria for

Acceptance

(a) The longitudinal and transverse sections

indicated in Fig. 1 shall be cross sectioned as closely

as possible through the center line of the weld. A

minimum length of 1 in. shall be provided for examina-

tion of each longitudinal specimen. The transverse

specimens shall be of sufficient length to include the

weld, the heat affected zone, and portions of theunaffected base material. Cross sections shall be pol-

ished, etched, and examined at a minimum of 25 times.

The dimensions of the fusion zone and penetration of

each weld of the transverse specimens shall be measured

to the nearest hundredth of an inch and recorded.

(b) Acceptance Criteria

(1) The outline of the fusion zone shall

be generally consistent in size and regular in shape

and uniformity of penetration.

(2) The examination of the weld area

shall reveal sound weld metal, complete fusion along

the bond line, and complete freedom from cracks in

the weld metal and heat affected zone.

(3) The Procedure Qualification Record(PQR) shall contain reference to the WPS used and

the results of the examinations prescribed in (b)(3),

(b)(4), and (b)(5) above, respectively.

(c) Performance Qualification Require-

ments and Acceptance Criteria

(1) Unless exempt by (c)(4) below, weld-

ing operators shall be qualified in accordance with the

following:

(a) The welding operator shall make,

in accordance with a qualified WPS, a test coupon at

least 6 in. long for peel test coupons for two ply weld-

ments within the thickness limitations of the table, as

shown in Fig. 2, sketch (a), and for all sheet thicknesses

in excess of 0.125 in. and for multiple sheet weldments,as shown in Fig. 2, sketch (b).

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CASE (continued)

2018-2

CASES OF ASME BOILER AND PRESSURE VESSEL CODE

FIG. 1 PROCEDURE QUALIFICATION TEST COUPON AND TEST SPECIMENS

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