Threadolet Rating for Refinery Appliction

In the first instance it seems we need to check temprature vs pressure table.

I havent got the table ; but we can start from there for 365 Deg F.

Regards,

ASME B16.11 doesn't cover 'olets. You have to look to MSS SP-97.

With that - there is no 2000# TOL - there is only 3000# and 6000#.

According to MSS SP-97:

2.2 Design temperature and other service conditions
shall be limited as provided by the applicable piping
code or regulation for the material of construction of
the fitting. Within these limits the maximum allowable
pressure of a fitting shall be that computed for
straight seamless run pipe of equivalent material (as
shown by comparison of composition and mechanical
properties in the respective material specifications).
The wail thickness used in such computation
shall be that tabulated in B36.1 OM for the size and
applicable schedule of pipe reduced by applicable
manufacturing tolerances and other allowances (e.g., threaded allowances).

I don't feel like running through the numbers right now - but why don't you calculate this, without neglecting corrosion allowance, and see what you find out.

Alternatively, whoever the spec is from may have had issues before with breaking 3000# threadolets due to vibration or rough-handling (sticky valves, mean operators, ..........) so that they have decided to only go with 6000#.

Something is funny with the 125 FF / 150 RF issue - Do you mean to say that you are installing class 125 Gray Iron B16.1 Flanges but rating them according to B16.5?

Or are you leaving out an important piece of history/information, such as: This spec at one time called for cast iron pipe, but was rewritten for steel pipe - hence, when old pipe is replaced you may have to mate a 125 FF to a 150 RF.

................ If so, you have to be careful, because when mating cast iron flanges to raised face steel flanges - usually the CI flange is flat and when it is tightened against the raised face it torques over and can lead to cracking in the cast iron body.

When this needs to be done it is usually recommended to machine the steel flange flat and install a full-face gasket.

To find the class/rating of a threaded connection:

1. Calculate the Pipe Wall Thickness of that pipe in which your fitting will be connected, by using the appropriate equation of ASME Code (may be B31.3), taking into consideration:

• Design pressure, • Design temp., • Corrosion allowance, and • Threading tolerance.

2. From step 1, find the pipe Schedule by using Tables of ASME B36.10M.

3. By using ASME B16.11, Table 2, find the Class of threading:

• Threaded fitting Class 2000 equivalent to pipe Sch. number 80 (Wall designation XS),

• Threaded fitting Class 3000 equivalent to pipe Sch. number 160, and

• Threaded fitting Class 6000 equivalent to pipe Wall designation XXS.

I don't agree that B16.11 is "fully" applicable to threadolets. I believe you must go to MSS SP97, and I don't think Class 2000 threadolets exist (apart from the Sch 5S and 10S "Pipets")

And according to MSS SP97 the sizes/pipe wall basis are

• Class 3000: NPS 1/8 - 4 : Extra Strong
• Class 6000: NPS 1/2 - 2 : Schedule 160

However, the procedure for calculating the thickness and correlating to B36.10 is the same.

(& I hope this isn't the New Year's booze talking )

My dear Guest and all CR4 members, Happy New Year.

I'd like to indicate that we are oil refining co., and in addition to that we are designers and fabricators for pressure vessels and heat exchangers. We held certificates of authorization for design, fabrication and repair of code items such as U, R and ISO 9001 since 1994. And we arrange to add 2 or 3 ASME Code stamps through the new year such as S, PP and VR.

And I see that ASME B16.11 is more restrictive compared with MSS SP97, which not only I prefer B16.11 in selecting the class of threaded fittings, but also I have to adapt with ASME Code rules for design calculations.

In addition to that I have to procure that fittings in accordance with the specifications of ASME B16.11 not MSS SP97.

Fair enough - and I respect that, but I still disagree that B16.11 does not fully apply to threadolets - only other forged threaded fittings (if you don't agree - please show me a Class 2000 threadolet)

MSS SP97 is fully qualified as per ASME B31.3 - 304.7.2:

(c) proof test in accordance with either ASME B16.9,
MSS SP-97, or Section VIII, Division 1, UG-101.

(if you don't agree - please show me a Class 2000 threadolet)

Yes, actually I don't agree you.

Even there is no Class 2000 Threadolet, the ASME B16.11 implements for all classes of threaded fittings starting from Class 2000, whatever that fitting is a half coupling, elbow, or threadolet. And Table 2 of ASME B16.11 (as noted from my post #3 ) stated that: Threaded fitting Class 2000 equivalent to pipe Sch. number 80 (Wall designation XS).

I think we are splitting hairs here / arguing a moot point.

The one point that (I hope) we both agree on, and should be the definitive basis is the requirement for calculating wall thickness.

I hate to beat this topic to death, nor do I want to come across as argumentative (because I truly do respect your knowledge/expertise, and the way in which you pose well thought out answers), but I believe this is a contentious issue, and I have had "arguments" with others regarding it.

But according to Bonney Forge's catalogue - page 15, they design their threadolets to MSS SP-97.

http://www.bonneyforge.com/resources/BC.pdf

And, from SP-97 : Class 3000 is XS pipe.

............... hmmmmmmmmm ............ I must concede (and blame my erroneous argument on the hang-over/drunkedness). It seems that I may have "won" this argument in the past based on the approach that SP-97 would be more conservative considering these numbers.

(these numbers are just for argument and may not be exactly as per required because I want to put this issue to rest and not waste any more time on it )

If you performed the pipe wall required calculation for, let's say 1" NPS, and came to a required thickness of 0.200" - as per B36.10M you would need a nominal pipe of Sch. 160

This, according to B16.11 would lead you to a Class 3000 threadolet (fair enough)

But, the SP-97 approach would lead you to a Class 6000 threadolet (conservative)

(It must be because of time zone differences, but I wish you would post before me so that I could critique your answers first)

(By the way, I noticed you literally gave me a "Good Answer" to the loadings question recently posted in the Manufacturing forum, but I didn't notice an official Good Answer [joking because I don't agree with the notion of Good Answers])

Anyways, will all due respect, thanks for straightening my out, and please keep me inline in the future.

For every code/standard there is a factor of safety^* used in design to be fellow by the users. For this reason, the pressure vessels designed and constructed in accordance with DIN have a thinner shell wall thickness than those designed by the ASME code. And when you apply ASME equations to those vessels designed under DIN, you will find it unacceptable per ASME code. And this "unacceptability" doesn't means that these vessels are refused or can not be used in practical.

The same thing exist when we compare ASME B16.11 to MSS SP-97, where B16.11 is more restrictive compared with SP-97 which is conservative. So, you have to apply the rules and recommendations of your code which will certify your products.

* The factor of safety used in ASME code itself is vary from section to another, as that is clear from the Allowable Tensile Strength stated by B31.1 Power Piping which is differ from that used in ASME B31.3 Process Piping. And I can proceed an example I used to demonstrate in my lecturers to my trainee allover the world for a piping system which is designed using the both codes: B31.1 and B31.3, where you can easily find that the pipe Schedule No. by using the rules of B31.1 is higher than that one if we apply the rules of B31.3.

• Data Given:

- Pipe Material : ASME SA 106 Grade B (seamless)

- Pipe Size : NPS 10"

- Design Pressure 1200 psi

- Design Temp. : 680 ^oF

- Corrosion Allowance : 0.0625 in.

• Results of calculations:

- By using the rules of ASME B31.3 : Pipe Schedule No. 60 (XS)

- By using the rules of ASME B31.1 : Pipe Schedule No. 80

• I will be glad if you proceed that example by yourself and prove the soundness of the results.

So, I think that there is no conflict between the both codes, only you have to select the code which will adapt your requirements, specifications and the contractual obligations

At the end: What do you think who own the argument? Please be fair.