ASME B16.25 Standard-Butt welding Ends

ASME B16.25 standard covers the preparation of butt welding ends of piping components to be joined into a piping system by welding.It includes requirements for
welding bevels,for external and internal shaping of heavy-wall components,and for preparation of internal ends (including dimensions and tolerances).Coverage includes preparation for joints with the following:

(a)no backing rings
(b)split or noncontinuous backing rings
(c)solid or continuous backing rings
(d)consumable insert rings
(e)gas tungsten arc welding (GTAW)of the root pass
Details of preparation for any backing ring must be specified when ordering the component.

Application of ASME B16.25 standard

ASME B16.25 standard applies to any metallic materials for which a welding procedure can be satisfactorily qualified but does not prescribe specific welding processes or procedures.Unless otherwise specified by the purchaser, it does not apply to welding ends conforming to ASME B16.5,ASME B16.9,or ASME B16.47.

Maximum Envelope for Welding End Transitions

NOTES:

1. 1. Where transitions using maximum slope do not intersect inside or outside surface,as shown by broken lines,maximum slopes shown or alternate radii shall be used.
   2. Weld bevel shown is for illustration only.
   3. The weld reinforcement permitted by applicable code may lie outside the maximum envelope.
   4. The value of tmin is whichever of the following is applicable:
      • (a)the minimum ordered wall thickness of the pipe to include pipe that is purchased to a nominal wall thickness with an undertolerance other than 12.5%
      • (b)0.875 times the nominal wall thickness of pipe ordered to a pipe schedule wall thickness that has an undertolerance of 12.5%
      • (c)the minimum ordered wall thickness ofthe cylindrical welding end ofa component or fitting (or the thinner of the two)when the joint is between two components
   5. The maximum thickness at the end of the components is

1. • (a)the greater of tmin 4 mm (0.16 in.)or 1.15tmin when ordered on a minimum wall basis
   • (b)the greater of tmin +4 mm (0.16 in.)or 1.10 times the nominal wall thickness when ordered on a nominal basis(see ASME B36.10 and ASME B36.19 for a tabulation of nominal wall thicknesses)

Bevels for wall thickness over 3mm to 22mm

GENERAL NOTES:

• (a)Broken lines denote maximum envelope for transitions from welding bevel and root face into body of component.See Figure 2-1 for details.
• (b)See section 5 for tolerances other than those given in these illustrations.
• (c)Purchase order must specify contour of any backing ring to be used.
• (d)Linear dimensions are in millimeters with inch values in parentheses.

NOTES:

• (1)Internal surface may be as-formed or machined for dimension B at root face.Contour within the envelope shall be in accordance with section 2.
• (2)Intersections should be slightly rounded.

Weld Bevel Details for Wall Thickness Over 22mm

GENERAL NOTES:

• (a)Broken lines denote maximum envelope for transitions from welding bevel and root face into body of component.See Figure 2-1 for details.
• (b)See section 5 for tolerances other than those given in these illustrations.
• (c)Purchase order must specify contour of any backing ring to be used.
• (d)Linear dimensions are in millimeters with inch values in parentheses.

NOTES:

• (1)Internal surface may be as-formed or machined for dimension B at root face.Contour within the envelope shall be in accordance with section 2.
• (2)Intersections should be slightly rounded.

Weld Bevel Details for GTAW Root Pass

GENERAL NOTES:

• (a)This detail applies for gas tungsten arc welding (GTAW) of the root pass where nominal wall thickness is over 3 mm (0.12 in.) to 10 mm (0.38 in.), inclusive.
• (b)Linear dimensions are in millimeters with inch values in parentheses.

Weld Bevel Details for GTAW Root Pass

GENERAL NOTES:

• (a)This detail applies for gas tungsten arc welding (GTAW) of the root pass where nominal wall thickness is over 10 mm(0.38 in.) to 25 mm (1.0 in.), inclusive.
• (b)Broken lines denote maximum envelope for transitions from welding groove and land into body of component. See Figure 2-1 for details.
• (c)See section 5 for tolerances other than those given in these illustrations.
• (d)Linear dimensions are in millimeters with inch values in parentheses.

NOTE:(1)Inside corners should be slightly rounded.

Weld Bevel Details for GTAW Root Pass

GENERAL NOTES:

• (a)This detail applies for gas tungsten arc welding (GTAW)of the root pass where nominal wall thickness is greater than 25 mm (1.0 in.).
• (b)Broken lines denote maximum envelope for transitions from welding groove and land into body of component.See Figure 2-1 for details.
• (c)See section 5 for tolerances other than those given in these illustrations.
• (d)Linear dimensions are in millimeters with inch values in parentheses.

NOTE:(1)Inside corners should be slightly rounded.

Table 3.3-1 Dimensions of Welding Ends (See Figures 2-1 Through 3.2-3)

GENERAL NOTES:
(a)Dimensions are in millimeters with inch values in parentheses.
(b)See section 5 for tolerances.

NOTES:
(1)Data are from ASME B36.10 and ASME B36.19 or a more precise rounding of the inch dimensions.Letter designations signify

• (a)STD standard wall thickness
• (b)XS extra-strong wall thickness
• (c)XXS double extra-strong wall thickness

(2)See para.3.3.
(3)Internal machining for continuous backing rings for connecting pipe having a wall thickness s 3.17 mm(0.125 in.)is not contemplated (see para.3.1).See para.4.2 for C dimension for sizes or schedules not listed.

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