ASME BPE code is the bioprocessing equipment code and covers 1/2" thru 6" tubular products.

The piping for example, may consist of stainless steel tubing such as stainless steel ASTM A270 Type 316L (UNS31603)with special internal/external surface polishing. Such systems are usually sterilized and so the thermal analysis is desirable.

Some challenging aspects of analyzing this piping to ASME B31.3 that I have found include:
1. Tees with clamp ends do not conform to ANSI B16.9 weld tees dimensionally, and fabrication results in a crotch region that is much different.
2. Tees are used with hygienic clamp ends, and so do not meet Note 13 of Table D300.
3. Elbow radius' do not match ANSI B16.9, radius for clamp end elbows are higher, and for automatic weld end elbows higher still, and the type to be used is not always known at analysis.
4. Hygienic clamp manufacturers have not been forthcoming on acceptable loads for their products, and the BPE code does not establish load ratings.

To model the tees I have used unreinforced fabricated tee SIFs, which can run 3-4 times that of a B16.9 tee. Carefull attention to ISOs will ususally predict where welding .vs. clamp ends for tees and elbows will be applied. Then bend radius' and flange factors can be entered accordingly. The owner and I agreed on a table of load values for hygenic clamps based on ASME B16.5 flange calculations to monitor clamp connection loads. The uncertainty with the tees installed without the straight pipe requirement is unaddressed, except for monitoring the results and adjusting the layout to keep the stress ratio for such tees well below unity.

How do others deal with these challenges? Are you using FEA methods to develop SIFs?

Thus the jackpot.... When you get off the beaten path you end up doing a research project that was not included in your estimate!

FEA yes that may help, but thats not so easy in itself, prototypical testing sure the best sort of answer.

BUT the $%&^#&$^*# manufacturer should be pressed into taking care of the design data required to use his product with some reliability! A discussion with the owner is a must because the owner may be able to put some leverage into the situation ($$$$$) that will get the attention of the manufacturer... these components are not listed so its all up to somebody other than the code!

Analysist beware!!!!!


I've done these (4" steam line) and a few notes:

1. The walls are thin, thus the Safety factors do not exist. be carefull with high temperature and pressures
2. Because the walls are so thin, there is not a lot of meat left in the pipe wall for structural purposes.
3.Visit site and have 100% confidence in the site construction team, the welding of these pipes is a complicated process and requires very good monitering and quality control.
4. for critical connections, visually inspect the welds. the fittings do not allow for any misallignment, but this is common place. make sure your critical fittings are welded good
5.Talk to the manufacturer of the fittings ESPECIALLY THE TEES!!!
The *cough* tees, should be extruded, but i discovered that due to production losses trying to keep to the asme tolerances, the manufacturer swithed to laser cut and welded. THIS NEGATED ANY ADVANTAGE OF THE CROTCH RADIUS!!!!
6. long runs cause high expansion, which need to be allowed to grow. good pipe supports are required here because the pipe will not push "jammed" supports, it will just buckle.
7.Cyles,- watch out for high cycling systems, (steam outs are notorious for this) i would be concerned about high cycling systems
8.Steam, causes surges, water hammer etc. treat the critical supports carefully and ensure the linestops can cope with and upset line conditions.
9.Buckling, long vertical rises, supported from the bottom are a no-no, these pipes dont cope with buckling very well.4


I switched off the Liberal stress allowance, and turned on the "EXTREME DANGER" botton on caesar.!!!!

I treated the analysis, not as an exercise in getting code compliance, but rather in modifying and adjusting the design so that the stresses were as low as i could possibly make them.

I can't recommend a site visit enough.
The last time i did one of these, the contractor installed all the supports wrong (welded them to the steam, hence anchors every where)


Finally, BPE pipes, to my mind are not suitable nor applicable to Stress Critical regimes. I try to get the client to use at least shd5 pipe, but this usually falls on deaf ears.

A expert on BPE piping is a god-send, (i had one a great guy)


Good luck

"Liberal stress allowance" I prefer to think of this as the computerized school of analysis allowance.

If you were looking at systems using manual calcs you simply did not take the time to calc the sustained stresses for the difference as in the computerized allowance, you used the lower so-called conservative (by some) or manual calc allowance.

This flimsy stuff may also have D/t ratios of over 100 so localized effects may be quite prominent.

John -

Thank you for responding. I have pressed three of the major manufacturers for load data on hygienic clamps. Ans as you have learned too, the outcome was letters from the manufacturers which stated "...stress and moment arm ratings..." are not provided, and "We do not recommend the use of the clamp connection as a load bearing member of a piping system." Subsequently, I have told clients that I can not comply with B31.3 and demonstrate with a beam-type analysis that the hygienic clamps will comply with B31.3, and I recommended that they avoid or minimize the use of the clamps.

Tim -

Thanks to you too for a thoughtful response. I have found the same issues with the tees. What do you do then to analyze the tees in a beam-type analysis? I have decided to use the SIF for unreinforced fabricated tee with SIFs of 6 to 8 and have told clients that is the best estimate I can make for the stress at the tees.

I also find that anchors that need to be welded to the pipe are not acceptable. Instead a clamping type polyproplyene anchor (which doubles as a guide with a spacer) is used (e.g. Behringer). Those anchors do not always hold. I am investigating the use of a pre-engineered and pre-insulated anchor using thrust plates welded to the BPE piping (e.g. Rilco, Pipe Shields). Any experience with this type anchor on BPE systems?

WRT Tees,
Thats exactly what i did. the manufacturers had no idea what sifs were.....

WRT Supports, Behringer state (somewhere) a axial restraint force of about 100lbs for there *cough* anchor.

Behringer have also designed a hygenic clamp with internal ridges to help friction, not sure of the Fig number though.

Be carefull with the hygenic supports., one needs to review the entire system including IFC isometrics to ensure clams/guides etc are correctly fixed. FYI we used the beringer anchor on most support points, and welded the stup to a slide plate as required, in other words we used the Anchor as a pipe fixment and controled the movements of the plate underneath ALA' normal pipe support practice and it worked well. (behringer supports nmaes are VERY misleading)

We did not use anchors (i Don't like moments) but we used the behringer anchor with a small (tacked) lug each side of the clamp to act as a line stop.(with low forces)

No re-pads etc as the welding was to difficult

WRT to clamp manufacturers, there comment is bull$hit. A support by definition takes load, pass the buck if you please.
The clamps are strong, way stronger than the pipe so anything not requiring friction will be fine. We used there clamps and designed our own slides etc.

It as i said all points to BPE being unsuitable for Stress pipework.

I did state to the client my inabillity to be 100% confident that the system was upto Code standards. They accepted the (miminal) risks which i reduced to a minimum.

But, you have to visually inspect the critical parts (tees/loops)yourself.
Very important.

Good luck.

(Oh, and WRT to liberl allowance, we used it as a ceiling check, crude but effective))