-
3
- #1
TomBarsh
Structural
- Jun 20, 2002
- 1,003
Some designers are questioning why COMPRESS applies joint efficiency E=0.85 (or 0.80) to calculation for required thickness based on circumferential stress for cones or transitions that have been fully radiographed on the longitudinal seam.
This results from relatively new rules in ASME Code. New rules exist for circumferential joints at cone-cylinder junction when the cone angle exceeds 30°. New weld joint Type 8 was added to Table UW-12 for angle joints.
Paragraph UW-3(b) has been revised to indicate that Category B circumferential joints (as at cone-cylinder) "are butt joints if the half-apex angle (alpha) is equal to or less than 30 degrees, and are the angle joints when alpha is greater than 30 degrees."
For cases where the cone is fully radiographed on the longitudinal seam the joint efficiency to be applied when determining required thickness based on circumferential stress as per UG-32(e) is defined in UG-32(b), which directs to use the efficiency specified in paragraph UW-12. Paragraph UW-12(a) indicates that the value of E shall be not greater than that given in column (a) of Table UW-12 except that when the additional requirements of UW-11(a)(5) are not met then the value of E shall not be greater than that given in column (b) of Table UW-12. Paragraph UW-11(a)(5)(a) indicates that all category B joints connecting the part must be Type 1 or Type 2. Because the circumferential joint in case of angle greater than 30° is angle joint Type 8 the rules of UW-11(a)(5) are not met. Consequently the joint efficiency E used for thickness calculation of the transition cannot be greater than that listed in column (b) of Table UW-12. With full radiography on the longitudinal joint the joint efficiency will be 0.85 for Type 1 joint and 0.80 for Type 2 joint.
"Although this forum is monitored by Codeware it is not intended as a venue for technical support and should not be used as the primary means of technical support."
Tom Barsh
Codeware Technical Support
This results from relatively new rules in ASME Code. New rules exist for circumferential joints at cone-cylinder junction when the cone angle exceeds 30°. New weld joint Type 8 was added to Table UW-12 for angle joints.
Paragraph UW-3(b) has been revised to indicate that Category B circumferential joints (as at cone-cylinder) "are butt joints if the half-apex angle (alpha) is equal to or less than 30 degrees, and are the angle joints when alpha is greater than 30 degrees."
For cases where the cone is fully radiographed on the longitudinal seam the joint efficiency to be applied when determining required thickness based on circumferential stress as per UG-32(e) is defined in UG-32(b), which directs to use the efficiency specified in paragraph UW-12. Paragraph UW-12(a) indicates that the value of E shall be not greater than that given in column (a) of Table UW-12 except that when the additional requirements of UW-11(a)(5) are not met then the value of E shall not be greater than that given in column (b) of Table UW-12. Paragraph UW-11(a)(5)(a) indicates that all category B joints connecting the part must be Type 1 or Type 2. Because the circumferential joint in case of angle greater than 30° is angle joint Type 8 the rules of UW-11(a)(5) are not met. Consequently the joint efficiency E used for thickness calculation of the transition cannot be greater than that listed in column (b) of Table UW-12. With full radiography on the longitudinal joint the joint efficiency will be 0.85 for Type 1 joint and 0.80 for Type 2 joint.
"Although this forum is monitored by Codeware it is not intended as a venue for technical support and should not be used as the primary means of technical support."
Tom Barsh
Codeware Technical Support