127 WELDING

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Fig. 127.3 Butt Welding of Piping Components With

Internal Misalignment

1/16 in. (2.0 mm) or less

30 deg max.

the socket to the maximum depth and then withdrawn approximately 1⁄16 in. (2.0 mm) away from contact between the end of the pipe and the shoulder of the socket [see Figs. 127.4.4(B) and (C)]. In sleeve-type joints without internal shoulder, there shall be a distance of approximately 1⁄16 in. (2.0 mm) between the butting ends of the pipe or tube.

The fit between the socket and the pipe shall conform to applicable standards for socket weld fittings and in no case shall the inside diameter of the socket or sleeve exceed the outside diameter of the pipe or tube by more than 0.080 in. (2.0 mm).

127.4 Procedure

Greater than 1/16 in. (2.0 mm)

may remain on the flame cut surface is not considered to be detrimental oxidation.

(A.2) Butt-welding end preparation dimensions contained in ASME B16.25 or any other end preparation that meets the WPS are acceptable.

(A.3) If piping component ends are bored, such boring shall not result in the finished wall thickness after welding less than the minimum design thickness. Where necessary, weld metal of the appropriate analysis may be deposited on the inside or outside of the piping component to provide sufficient material for machining to insure satisfactory fitting of rings.

(A.4) If the piping component ends are upset, they may be bored to allow for a completely recessed backing ring, provided the remaining net thickness of the finished ends is not less than the minimum design thickness.

(B)Cleaning. Surfaces for welding shall be clean and shall be free from paint, oil, rust, scale, or other material that is detrimental to welding.

(C)Alignment. The inside diameters of piping components to be butt welded shall be aligned as accurately as is practicable within existing commercial tolerances on diameters, wall thicknesses, and out-of-roundness. Alignment shall be preserved during welding. The inter-

nal misalignment of the ends to be joined shall not exceed 1⁄16 in. (2.0 mm) unless the piping design specifically states a different allowable misalignment.

When the internal misalignment exceeds the allowable, it is preferred that the component with the wall extending internally be internally trimmed per Fig. 127.3. However, trimming shall result in a piping component thickness not less than the minimum design thickness, and the change in contour shall not exceed 30 deg (see Fig. 127.3).

(D)Spacing. The root opening of the joint shall be as given in the WPS.

(E)Socket Weld Assembly. In assembly of the joint before welding, the pipe or tube shall be inserted into

78

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127.4.1General

(A)Qualification of the WPS to be used, and of the performance of welders and operators, is required, and shall comply with the requirements of para. 127.5.

(B)No welding shall be done if there is impingement of rain, snow, sleet, or high wind on the weld area.

(C)Tack welds permitted to remain in the finished weld shall be made by a qualified welder. Tack welds made by an unqualified welder shall be removed. Tack welds that remain shall be made with an electrode and WPS that is the same as or equivalent to the electrode and WPS to be used for the first pass. The stopping and starting ends shall be prepared by grinding or other means so that they can be satisfactorily incorporated into the final weld. Tack welds that have cracked shall be removed.

(D)CAUTION: Arc strikes outside the area of the intended weld should be avoided on any base metal.

127.4.2Girth Butt Welds

(A)Girth butt welds shall be complete penetration welds and shall be made with a single vee, double vee, or other suitable type of groove, with or without backing rings or consumable inserts. The depth of the weld measured between the inside surface of the weld preparation and the outside surface of the pipe shall not be less than the minimum thickness required by Chapter II for the particular size and wall of pipe used.

(B)To avoid abrupt transitions in the contour of the finished weld, the requirements of (B.1) through (B.4) below shall be met.

(B.1) When components with different outside diameters or wall thicknesses are welded together, the welding end of the component with the larger outside diameter shall fall within the envelope defined by solid lines in Fig. 127.4.2. The weld shall form a gradual transition not exceeding a slope of 30 deg from the smaller to the larger diameter component. This condition may be met by adding welding filler material, if necessary, beyond what would otherwise be the edge of the weld.

(B.2) When both components to be welded (other than pipe to pipe) have a transition from a thicker section to the weld end preparation, the included angle between

30 deg max.

Maximum slope 1:3

Radius of at least 0.05tm

Transition region

GENERAL NOTES:

(a)The value of tm is whichever of the following is applicable:

(1)as defined in para. 104.1.2(A)

(2)the minimum ordered wall thickness of the cylindrical welding end of a component or fitting (or the thinner of the two) when the joint is between two components

(b)The maximum envelope is defined by solid lines.

NOTES:

(1)Weld is shown for illustration only.

(2)The weld transition and weld reinforcement shall comply with paras. 127.4.2(B) and (C.2) and may be outside the maximum envelope.

(3)The maximum thickness at the end of the component is

(a)the greater of (tm + 0.15 in.) or 1.15tm when ordered on a minimum wall basis

(b)the greater of (tm + 0.15 in.) or 1.10tnom when ordered on a nominal wall basis

79

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the surface of the weld and the surface of either of the components shall not be less than 150 deg. Refer to para. 119.3(B) for additional concerns related to this design.

(B.3) When welding pipe to pipe, the surface of the weld shall, as a minimum, be flush with the outer surface of the pipe, except as permitted in para. 127.4.2(B.4).

(B.4) For welds made without the addition of filler metal, concavity shall be limited to 1⁄32 in. (1 mm) below the outside surface of the pipe, but shall not encroach upon minimum required thickness.

(C) As-welded surfaces are permitted; however, the surface of welds shall be sufficiently free from coarse ripples, grooves, overlaps, abrupt ridges, and valleys to meet the following:

(C.1) The surface condition of the finished welds shall be suitable for the proper interpretation of radiographic and other nondestructive examinations when nondestructive examinations are required by Table 136.4. In those cases where there is a question regarding the surface condition on the interpretation of a radiographic film, the film shall be compared to the actual weld surface for interpretation and determination of acceptability.

(C.2) Reinforcements are permitted in accordance with Table 127.4.2.

(C.3) Undercuts shall not exceed 1⁄32 in. (1.0 mm) and shall not encroach on the minimum required section thickness.

(C.4) If the surface of the weld requires grinding to meet the above criteria, care shall be taken to avoid reducing the weld or base material below the minimum required thickness.

(C.5) Concavity on the root side of a single welded circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinner member of the two sections being joined and the contour of the concavity is smooth without sharp edges. The internal condition of the root surface of a girth weld, which has been examined by radiography, is acceptable only when there is a gradual change in the density, as indicated in the radiograph. If a girth weld is not designated to be examined by radiography, a visual examination may be performed at welds that are readily accessible.

127.4.3 Longitudinal Butt Welds. Longitudinal butt welds not covered by the applicable material specifications listed in Table 126.1 shall meet the requirements for girth butt welds in para. 127.4.2. For longitudinal welds and spiral welds in pipe intended for sustained operation in the creep range (see paras. 104.1.1 and 123.4, and Table 102.4.7), any welding using the SAW process shall use a flux with a basicity index ≥ 1.0.

127.4.4 Fillet Welds. In making fillet welds, the weld metal shall be deposited in such a way as to secure adequate penetration into the base metal at the root of the weld.

Fillet welds may vary from convex to concave. The size of a fillet weld is determined as shown in Fig. 127.4.4(A). Typical minimum fillet weld details for slip-on flanges and socket-welding components are shown in Figs. 127.4.4(B) and (C).

127.4.5 Seal Welds. Where seal welding of threaded joints is performed, threads shall be entirely covered by the seal weld. Seal welding shall be done by qualified welders.

127.4.8Welded Branch Connections

(A)Welded branch connections shall be made with full penetration welds, except as allowed in para. 127.4.8(F). Figures 127.4.8(A), (B), and (C) show typical details of branch connections with and without added reinforcement. No attempt has been made to show all acceptable types of construction and the fact that a certain type of construction is illustrated does not indicate that it is recommended over other types not illustrated.

by welding half couplings or adapters directly to the run pipe.

Figure 127.4.8(E) shows branch connections using specifically reinforced branch outlet fittings welded directly to the run pipe. These branch connection fittings, half couplings, or adapters, which abut the outside surface of the run wall, or which are inserted through an opening cut in the run wall, shall have opening and branch contour to provide a good fit and shall be attached by means of full penetration groove welds except as otherwise permitted in (F) below.

The full penetration groove welds shall be finished with cover fillet welds and meet the requirements of para. 104. The cover fillet welds shall have a minimum throat dimension not less than that shown in Fig. 127.4.8(E) or Fig. 127.4.8(F), as applicable.

(D) In branch connections having reinforcement pads or saddles, the reinforcement shall be attached by welds at the outer edge and at the branch periphery as follows:

(D.1) If the weld joining the added reinforcement to the branch is a full penetration groove weld, it shall

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Table 127.4.2 Reinforcement of Girth and Longitudinal Butt Welds

the width of the weld in inches (millimeters).

GENERAL NOTES:

(a)For double welded butt joints, this limitation on reinforcement given above shall apply separately to both inside and outside surfaces of the joint.

(b)For single welded butt joints, the reinforcement limits given above shall apply to the outside surface of the joint only.

(c)The thickness of weld reinforcement shall be based on the thickness of the thinner of the materials being joined.

(d)The weld reinforcement thicknesses shall be determined from the higher of the abutting surfaces involved.

(e)Weld reinforcement may be removed if so desired.

81

xmin. xmin.

xmin. xmin.

xmin. xmin.

Fig. 127.4.4(C) Minimum Welding Dimensions Required for Socket Welding Components Other Than Flanges

tn = nominal pipe wall thickness

Cx

Cx (min.) = 1.09tn or the thickness of the socket wall,

whichever is smaller

Cx

Approximately 1/16 in. (2.0 mm)

before welding

Fig. 127.4.8(B) Typical Welded Branch Connection

With Additional Reinforcement

Vent hole

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-`,,`,,`,`,,` --- Copyright ASME International

Provided by IHS under license with ASME

No reproduction or networking permitted without license from IHS

83

Not for Resale, 03/08/2011 00:55:16 MST

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