Pressure/Temperature ratings for Class 150 Titanium Flanges ? 3

[MJCronin]

hello all....

Does anyone have pressure/temperature ratings for Class 150 (construction) Titanium Flanges ?

ANSI B16.5 does not cover any Titanium material. I am intersted in TI Grades 2 and 7

I have been through many websearches and cannot find this.

I have contated the major USA Titanium pressure vessel vendors who said that they cannot help me.

I have been told that the methods of ASME VII must be used in each individual case.

Anyone ??????

 

[marty007]

One route would be to do an ASME VIII, Div1, Appendix 2 calculation. Unfortunately this would result in gasket dependent ratings.

 

[XL83NL]

I was in the same spot some time ago too, and somehow I was not surprised one could easily get WNRF B16.5 Ti Gr 2 flanges - from stock!
Just as easy as a 3x1" red tee to B16.9.

Market sells a man's demands.

I'd vote for ASME VIII Div 1 app 2 (or Div 2) calc.
Another route (even better - but more complex) is that of EN 1591-1 (and EN 1092-1); it's known ASME lacks in improvement whereas EN is more correct.
Or contact a vessel fab who does Ti vessels all the time and ask them for their experience to give you a quick start.

 

[doct9960]

MJCronin,

How about using lapped joint flanges?

The stub end would be titanium and the lapped flange could be carbon steel or stainless steel.

 

[ConstantEffort]

Can you correlate the properties of titanium with another material which is listed in B16.5?

At temperature, find a material with a similar allowable stress value and another with a similar elastic modulus and take the lesser of those two materials' flange ratings.

 

[MJCronin]

I was looking for some other way, or to take advantage of the work by others that have addressed this issue.

I do not wish to perform a custom ASME VIII calculation for each pipe size and for each particular gasket choice.

doct9960,

Yes, I will also be using lap joint flanges with CS backers.......

Based on your comment, are you implying, that the pressure-temperature rating of that joint is the same as that for the CS flanges ? (Class 150 in my case ?)

Titanium flanges have been around for 50 years or more.....

Someone has tables of Pressure-Temperature ratings.....

 

[XL83NL]

There are no B16.5 p,T-rating for Ti gr 2 afaik. The method by doct9960 is an excellent approach!

Use the p,T-rating of the CS [or 316 - whatever suits the service] backing ring (actually LJ flange), and do the pipe wall thickness calc for the B16.9 Ti stub end to e.g. B31.3 (assuming thats your design code).
Make sure you select the proper stub end to B16.9 (there's a short pattern and a long pattern). Make sure to get the right facing on the stub end.
This should help you; this approach helped me some time ago too (amazing how easily forgot to mention this - a star for doct9960)

When even this doesnt help you; try the EN approach, i.e. there are also standardized EN flanges for Ti with known ratings.
There are numerous German companies using these Ti flanges to EN specs (formerly known as DIN). Im sure there's a way to use them under B31.3 work.

 

[moltenmetal]

Titanium isn't a B16.5 material, so the ratings do not exist. And with good reason: lap joint construction and clad blinds are generally used to conserve the expensive material in materials like Ti, Zr etc. services which are not externally wetted.

That they are readily available is also not a surprise- I've observed the same thing. We use them to make tubing connections to teflon-lined carbon steel piping from time to time. It's been my experience that pipe/fitting supply houses will offer you whatever you want, machined out of a piece of bar or even plate, if you are willing to buy it. I have a pair of 3/4" 900# (i.e. 1500#) threaded titanium flanges that a former colleague ordered- they were manufactured from plate, as evident from the cutting marks on the OD which were not even machined away. We didn't install them because we didn't know how to rate them- and because they weren't necessary in the 1st place.

You can do appendix 2 calculations on every size and type if you like- if I had those calcs done I'd send them to you. Or you can use lapjoint construction to minimize the use of titanium, which is what most people do. Or if the design temperature is low, you can compare the stress values against those of 304 or 316SS and use the same rating as flanges in those materials. As far as I remember, the safe allowable stress values between 316L and Ti gr 2 (7 is just 2 with ~0.2% Pd added) are similar at ambient temperature, but SAS in Ti grades all fall off rapidly toward 315 C (600 F) where the material turns in to a pumpkin as far as ASME is concerned.

Some of the `50# flange designs in B16.5 fail appendix 2 at their B16.5 rated pressure/temperature right off the bat IIRCC, and others seem to de-rate in pressure faster than you would expect from stress values of the material alone, so you'd be safest with the App 2 calc.

 

[MJCronin]

Soooo... What is suspected is true !

As I stated, and so many others repeated, ASME B16.5 does not cover any titanium materials and, of course, it is always possible to perform an ASME VIII calculation for the particular flange diameter and gasket material.

But .....nobody really cares because lap-joint flanges are so often used....

and "as long as the temperature isn't too high" its OK to substitute the SS allowable stresses.

Seems like a poor state of affairs.....

Let's just say we have a Ti lap-joint piping flange at 450F/50 psig ( say 20"NPS, schedule 10S TI piping)

How can I prove to the client that the joint is acceptable ?

Do I refer to this thread ? or perhaps a paragraph in some code somewhere ? ? ? ? ? ?

 

[XL83NL]

Depending on your design code, what you could do if it's for piping to B31.3 - and take UNS R50400 for Ti gr 2;
- define a pipe spec, with B31.3 materials and components, and
- incl. e.g. ASTM B363 WPT2 for Ti gr 2 fittings. This is your material for the lap joint stub end, either long or short pattern, to ASME B16.9. The lap joint stub end is butt welded to a pipe. B363 is not B31.3 listed, but an ASME II material - otherwise, use e.g. a forging to ASTM B381.
- add a CS or SS lap joint flange as the backing ring, e.g. ASTM A105N or ASTM A182 F304
- do the wall thickness calcs to para 304.1.2, using stress values from table A-1 for UNS R50400.
- read the relevant ASTM specs you refer to in your pipe spec. For example, take ASTM B861 grade 2 for Ti gr 2 pipe. Determine all relevant parameters for the wall thickness calcs. The part on the ASTM is required to get your mill underrun tolerance.
- do the math (i.e. throw in all the values in the formula for all sizes) to determine your required minimum Code wall thickness for your required p,T-rating
If you want, I can give you a quick basic spec. I made one myself not so long ago for B31.3 piping.

I would not recommened you refer to this thread, but make sure you master the facts yourself. Read the (required) Code (sections).
If you understand it, you can explain it to another one too way more easily. This will be a better approach to convince anyone on this subject, rather than referencing to something you might not know yourself.

When it's for a vessel, do the same, except you have to use the vessel's Code rules for min. required wall thickness. For VIII-1 work, Im not that experienced to give you a quick start, but Im sure others here can give you a hand.

 

[XL83NL]

Im somewhat surprised you once wrote a FAQ on this forum for determining pipe wall thickness, whereas my last reply in it's essence is trying to tell you the same thing ...

Make sure you use a B16.9 lap joint stub end, and determine the wall thickness of the welding end part of this stub end to B31.3 internal pressure formula.
The lap joint stub end (either long or short pattern) will have a schedule designated just as for piping. It's just a piece of pipe with a collar.
For fabrication; make sure the welder throws on the backing flange around the pipe first before making the weld ;-).

Also, read B16.9 para 1.3; this gives you an escape to fabricate lap joint stub ends from long./spiral welded pipe to ASTM B862, which may make it easier to get a hold of them.

 

[doct9960]

doct9960,

Yes, I will also be using lap joint flanges with CS backers.......

Based on your comment, are you implying, that the pressure-temperature rating of that joint is the same as that for the CS flanges ? (Class 150 in my case ?)

Yes.

Let's just say we have a Ti lap-joint piping flange at 450F/50 psig ( say 20"NPS, schedule 10S TI piping)

How can I prove to the client that the joint is acceptable ?

If the code of construction is ASME Section VIII, Div. 1, I would refer your Client to UG-44. For the CS lap joint flange, the P-T rating is per ASME B16.5. For the ASME B16.9 Ti stub end, the P-T rating according to UG-44 "shall be calculated as for straight seamless pipe in accordance with the rules of this Division including the maximum allowable stress for the material."

I believe you can even fabricate the stub end as long as it meets the weld and thickness requirements in Fig. 2-4 of Appendix 2; and the dimensional requirements in ASME B16.9 for the radius of fillet, diameter of lap and OD of barrel.

Back in 2010, I was involved in the design of a brick-lined autoclave vessel that has Alloy 59 (UNS N06059) dip pipes. The code of construction for the dip pipes was ASME B31.3. I specified SA-105 lap joint flanges and Alloy 59 ASME B16.9 stub end fittings. The vessel manufacturer ended up fabricating the stub ends with pipe (for the barrel) and plate (for the lap). They probably had a hard time sourcing the Alloy 59 fittings.

 

[MJCronin]

Thank you for all of your comments.......

I am sure that these clarifications and methodologies will benefit the millions of young and smart third world engineers who will seek an answer to, what I feel, is a problem that has gone on for too long.

Please indulge a petulant, sulking old engineer...... teetering on the precipice of Social Security.....

Why hasn't ASME B16.9 defined pressure and temperature ratings for the common grades of titanium ?

They certainly have gone to the trouble and defined ratings for a variety of other crappy, rarely used materials !!!!

Also, why haven't the major vendors of Titanium pressure vessels and piping developed tables for piping and flanges ?

They sure as hell like to sell thier products and services.... As far as providing fundamental useful technical information ?..........Ummm.........no !

Any thoughts from this esteemed group ?

 

[moltenmetal]

Flanges are B16.5, not B16.9

Ask ASME, I have no idea why they haven't established ratings for solid Ti flanges. Personally I'm just glad they haven't, because if they had, ignorant clients who think they know better will request solid titanium flanges of me when lap joint/clad blind construction would be much more sensible. I've seen projects killed by the uninformed but inflexible desire for solid construction in exotic materials in past, and hate to see projects die unnecessarily. Even though they make me more money when they go ahead, I also hate to see precious, high environmental impact materials used in a wasteful fashion.

 

[SnTMan]

It is kind of a mystery. You can also buy 410SS and PVC flanges of B16.5 pattern, neither is a listed material, neither has a standard PT rating.

Quote: "The world is full of things you can buy. Not all are suitable for use in Code pressure vessels". (me)

Regards,

Mike

 

[XL83NL]

Back here in the Netherlands, soft drugs are legal, but hard drugs arent ... every wondered how easy you can get ´em and why their demand is so high?