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Interpretation: VIII-78-08

Subject: Section VIII, Division 1; UW-3

Date Issued: January 16, 1978

File: BC77-627

Question: Please verify that the following statements are correct with regard to interpretation of

UW-3:

(1) UW-3(a) weld Categories define the location of a joint, but not the type of joint.

(2) Category C merely locates the joint. This Category includes all types of flange to nozzle

neck connections.

(3) The butt welded joint connecting a welding neck flange to a nozzle neck is classified as

Category C and not Category B, although both are circumferential butt welded joints in a nozzle

(4) An intermediate circumferential butt weld joining two lengths of pipe in a nozzle neck, such

as may be found in a drain line, is classified as Category B.

(5) The weld categories do not describe the type of joint as indicated in Table UW-12.

(6) The weld categories do not define the nondestructive examination requirements.

(7) The requirements for the type of weld joint and nondestructive examination are dependent on

design and service considerations and are specified elsewhere in the Code.

(8) UW-11(b) and Note: All Category B and C butt welds in nozzle necks, including those

exempted on the basis of size from full radiography in UW-11(a)(4) or partial radiography in UW-

11(a)(5)(b), shall at least be examined by spot radiography according to UW-52. The frequency of the

spot examinations is defined in UW-52(b).

Reply: We agree with the above interpretations of UW-3.

Interpretation: VIII-78-09

Subject Section VIII, Division 1; U-1(d)(2)

Date Issued: January 16,1978

File: BC77-753

Question: An evaporator or condenser has a water side comprised of heads and tubes, which

represent an independent pressure chamber of a multiple chamber vessel. Does the 120 gal limitation of

U-1(c)(6) apply to the sum of the volumes of the tubes and heads?

Reply: Yes.

Interpretation: VIII-78-10

Subject: Section VIII, Division 1, UG-101, Proof Testing

Date Issued: January 16,1978

File: BC77-756

Question: Under the formulas of UG-101, proof testing, the formulas to compute the maximum

allowable working pressure of the vessel are reduced based on the ratio of the specified minimum yield

or tensile strength over the actual average strength from test specimens. On what basis is the maximum

allowable working pressure reduced by this ratio?

Reply: Although the actual average strength from test specimens as specified in the inquiry may

be greater than the specified minimum strength required by the materials specification, the proof test in

UG-101 are utilized for duplicate parts of the same materials, design, and construction which need not be