ASME B16.25:2017 pdf free download

ASME B16.25:2017 pdf free download
ASME B16.25:2017 pdf free download.Buttwelding Ends
Tables 1 and l-1 listthe Cvalues for pipe with an under- tolerance on A of0.79 mm (0.031 in.) and 12.5% on wall thickness forDN 50 to DN 1500 (NPS 2 to NPS 60) pipe. An undertolerance on A of0.4 mm (0.015 in.) and wall thick- ness of12.5% was used for DN 40 (NPS 1 1 / 2 ) and smaller pipe. For pipe with an A or pipe wall thickness underto- lerance other than the above, do not use the C data from Tables 1 and I-1 [see para. 4.3(a)].
4.3 Exceptions
(a) Forpipeortubingvaryingfromthe ASTM A106 and A335 types, having different wall thickness and/or outside diameter tolerances (such as forged and bored pipe), the foregoing equations may be inapplicable. Equations (1) and (2) may be used to determine C for these applications. The purchaser shall specify the C dimension when Tables 1 and I-1 data do not apply.
(b) For components in smaller sizes and lower sched- ule numbers, itmaybe necessaryto depositweld metal on the inside diameter (I.D.) or use thicker wall materials in order to machine the backing ring while maintaining required wall thickness. This condition may also arise when using material whose nominal dimensions indicate sufficient metal but whose actual I.D., considering toler- ances, is large enough to require additional metal.
5.1 Dimension B
Values for the I.D. at the welding end [see dimension B, Figure2,illustrations(a) and(b) andFigure3,illustrations (a) and(b)] shall be as specifiedin the applicable standard or specification for the component.
Large diameter pipe and fittings with a relatively thin wall have a tendencyto springout-of-round afterremoval from the machiningfixture. For this reason, the measured diameters mayvarywith orientation. Atolerance of+0.25 mm (+0.010 in.) applies to the average C diameter in Figures 2 and 3, illustrations (c) and (d). A tolerance of +0.25 mm, −1.02 mm (+0.010 in., −0.040 in.) applies to the average C diameter for Figures 5 and 6.