Q1 Would it be accurate to say to the owner that welding other than two pipe diameters of straight pipe to a tee in steam piping would not have been acceptable under the B31 code unless a shell/brick type finite analysis was performed of the tee and adjacent component?

A1: No the code does not specifically prohibit this but simply states if you do so the SIFs given may not be cuurate.

Q2: Did earlier codes assume that designers understood the two pipe diameter minimum spacing from other published works? What publications? Was the spacing just not understood to be a potential problem until Rodenbaugh's work in 1987?

A2: No, note was added for clarification...

Q3:As Rodenbaugh states in WRC 329, "We would rate the relative complexity of i-factors for pipe, elbows, and branch connections by the ratios 1:5:500." So, at this point in time, are there no other means (by WRC, Section III, or others) to evaluate such tee on fitting or tee on flange/valve fabrications other than shell/brick type finite element analysis?

A3:Yes. Prototype testing or as you mentioned...

Q4: Does the more recent understanding of the limitation of SIFs values for branch connections mean that it is advisable that owners assess older piping systems with congested piping arrangements because stresses in branch connections may be higher than once thought?

A4:Code rules are not retroactive per se. The codes are evergreen and hopefully change as information and understanding grows. See API 579 and take a trip into the realm of fitness for service...


Q5: Or can owners relax since steam systems are typically subject to low cycle fatigue, and will the 20% or so relief for under 3125 cycles and other conservative judgments mean very few systems will begin to leak due to fatigue cracks?

A5: Speculation can only answer this question, but more people than I have often said that low cycles n have saved many a system from failure.

Q6:Have I missed the "Recall" notice from the authority having jurisdiction or missed something else altogether?

A6: Nope, its all nebulous for many reasons some of which have to do with burning trains. Judgement and experience are prerequisites that are essential.

Good questions anybody else have their take on them????