Transcript Attachment J - Fowler - API SC6 June 2013 Presentation on Std 6X

API Standard 6X: Design
Calculations for PressureContaining Equipment
New Draft Standard under
Subcommittee 6
Task Group Membership
•
•
•
•
•
•
•
•
•
•
•
•
•
•
John Fowler – On-Line Resources - Chairman
Jim Britton – Cameron – 17D and 16C
Paul Bunch – Cameron – 16A and 17D
Jean Brunjes – GE – 6A
Bill Carbaugh – GE – 16A
Maynard Chance – West Engineering – All specs
Chris Johnson - NOV – 16A
Jim Kaculi – DrilQuip – 17D
Chris Kocurek – Cameron – 17D
John McCaskill - Expro – 16C
Nigel McKie – FMC – 17D
Mark Miser – DNV – All specs
Ramon San Pedro – Stress Engineering – all specs
Alireza Shirani – Cameron – All specs
History and Objective
• API 6A, 16A, and 16C referenced the ASME
Code Section VIII Division 2, 2004 Edition,
Appendix 4.
• Since referencing an obsolete spec is awkward, an
Annex (Annex I) was prepared for 16A capturing
the method from that ASME Appendix.
• Subcommittee 6 proposed that the method be put
in a separate document to assure uniformity.
Task Group Charge
• Create a new API standard documenting the
rules of the ASME Code, based on Annex I.
• Problem: 16A and 6A used different allowable
stresses.
Stress value
Spec 6A requirement
Spec 16A requirement
Max SI at test
pressure
5/6 of Sy
90% of Sy
Sm for standard
materials
2/3 of Sy
2/3 of Sy
Sm for non-standard
materials
Lower of 2/3 Sy or ½ Su
2/3 of Sy
Resolution
• The task group consensus was to use the rules of
16A, since going to the slightly more conservative
6A rules would penalize 16A/16C users who had
designed to higher allowable stresses.
• The 90% of Sy used in 16A and 16C is the same
as the limit in the 2004 ASME Code Section VIII
Division 2
• Using only the yield strength as a basis follows
Section VIII Division 3 practice.
Changes to Annex I
• Several revisions were made to the Annex I
document to clarify the requirements,
including several changes to the wording..
• The uses of limit analysis and elastic/plastic
analysis were clarified.
• The requirement on the sum of the three
principal stresses was clarified as to the
calculation basis.
Status of the draft Standard
• The TG finalized the draft and agreed it was ready
for ballot.
• API edited the document into standard API format
and returned it to the TG for review.
• After review the draft standard was be sent out for
ballot by SC6, with an April 30 deadline.
• SC 16 and SC 17 solicited comments from their
member companies, which will be considered
along with those from SC6 members.
Status of the ballot
• The ballot passed, with four negative votes.
• Over 150 comments were made, which the TG
has resolved.
• A TG meeting was held May 14 and the negative
voters were invited to attend.
• Three of the negative voters agreed to withdraw
their negatives, and the fourth was unable to
attend.
• Another TG meeting was held June 13, and all
negative ballots have been resolved.
Revisions resulting from resolution
of the ballot comments
• Numerous editorial changes have been made, including
moving material around to clarify requirements and
follow the API Style Guide more closely.
• An introduction was added to give background of the
standard.
• Definitions, abbreviations, and symbols were added, as
well as equations showing requirements.
• Stress components may be combined using vonMises
equivalent stress (vs. stress intensity) if permitted by
the product specification.
Revisions, cont.
• Removed the note that if the material has a high
yield/tensile ratio a lower Sm value may be used.
This makes the Sm determination exactly like in
16A and 16C.
• “Shall” substituted for more vague language
several places to clarify that requirements are
required.
• Title changed to “Design Calculations for
Pressure-containing Equipment.”
• An “Extreme Conditions” paragraph will be
added providing the “k” factor from ASME code.
Next Steps
• After agreeing on disposition of all comments, the
edited document and comment matrix are being
returned to API. API can then, depending on the
extent of the changes:
– Accept the changes and publish the document
– Recirculate the document for further comment
– Re-ballot the document
• Hopefully a new standard will be ready to be
referenced by the new editions of 6A, 16A, and
16C.
Follow-on actions after publication
of the new Standard
• Specifications 6A, 16A and 16C should revise
their design section to direct the designer to this
new standard instead of the 2004 Code.
• This may require several changes in the body of
the specifications.
• Since 17D refers to 6A for design requirements,
no change is needed.
• The 2004 ASME Code Section VIII Division 2
can be removed as a referenced standard, and
Standard 6X added.