Question and Answer 81-90

Question 90: relatie tussen toelaatbare druk en benaming

Beste Werner,

Vraag over ASME B16.5:

Ik neem als willekeurig voorbeeld het volgende vergelijk bij een Class 600 flens:

  • Metric: Group 1.1 Class 600 @ 20grC ð Pmax = 102.1barg
  • Imperial: Group 1.1 Class 600 @ 68grF ð Pmax = 1480psig

De verhouding is 1480 / 102.1 = 14,4956 hetgeen nagenoeg de "bar to psi" conversiefactor is van 14,5037738...


Is er enige relatie te vinden tussen de algemene benaming "Class 600" en de toelaatbare druk van een betreffende flens?

Je kunt gewicht omrekenen van pounds (lb) naar kilogram (kg) en omgekeerd, maar waar staat "lbs" voor en wat is dan de relatie tot de druk in barg of psi?

Druk is een kracht per oppervlak. Volgens tabel 4 hebbens RF flenzen, ongeacht de drukklasse, de zelfde dichtlijst-diameter en dus een constant oppervlak. De kracht neemt toe naarmate de druk hoger wordt. Is hier de relatie in te vinden?

Bijvoorbaad dank, / Kind regards
ing. R.S. DijkmansMechanical Engineer R&D

Answer from Werner Sölken

Beste Ron,

Op pagina Pressure Class vertel ik het e.e.a. over drukklasses van flenzen.

Voor wat betreft de dichtlijst-diameter; ik neem aan, dat de raised face van een flens bedoeld wordt. Het is juist dat RF flenzen, vervaardigd volgens ASME B16.5, ongeacht de drukklasse, allen de zelfde dichtlijst-diameter hebben.

Er is echter een verschil in de hoogte van de RF. Bij RF flensen tot en met drukklasse Class 300 is de hoogte circa 2 mm. Bij de drukklassen Class 400 tot en met 2500 is de hoogte circa 6,5 mm.

Op pagina Flange Faces kan je meer vinden over de verscheidene "flange faces".

Groeten Werner

Question 89: looking for a rubber bellow (expansion joint) manufacturer

Dear Werrner,
I hope you are doing fine. I'm a user of wermac website. I need your help. I'm looking for a rubber bellow (expansion joint) manufacturer who can perform hydro test and expansion test and give these reports for our review during third party inspections. The problem we face is that most manufacturers are refusing to provide the expansion test report(axial and lateral compression/expansion) on these bellows, which are to be used for water service application(AWWA). I do not understand why this is so.

Could you please suggest to me a good manufacturer from Europe who can supply us with the material along with these test reports?
Your help will be appreciated

Best Regards
Suhas Anil
Sr. Sales Engineer

Answer from Werner Sölken

Hi Suhas Anil,

On page Expansion Joints is a picture of a rubber expansion bellow displayed. I took the photo, but it was a project of my colleague Brian Gibson. I know that that particular Bellow, relatively high temperatures needed to "resist", but I have no further details. I will ask Brian for more information ... please be patient

greetings Werner

Answer from Werner Sölken

Hi Suhas Anil,
I just searched the internet and came against the sites below; I think they can answer your question.


greetings Werner

Question 88: today, minor errors will be reported for your reference

Dear Mr. Werner Sölken,

I really appreciated your Web.
Today, minor errors will be reported for your reference.
(1) End Cap
Bottom of ""
Description and Links are confused with "Dimensions threaded Caps".

(2) Pipe Material
Table "ASTM Grades" in
Carbon Steel Alloy Low-Temp "A333 Gr 5" shall be "A333 Gr 6".

Any way, I introduced your Web to my friends as the one of my favorites.

Takashi Komatsu
Mitsui Engineering and Shipbuilding Co. Ltd
Plant Engineering Div. Piping Design Dept

Answer from Werner Sölken

Hi Takashi Komatsu,

I have two "errors" corrected. Thank you.

greetings Werner

Question 87: i would like to learn as much as i could as i'm not from any engineering

Dear Werner,
Thank you so much for your website. Your Information on All Piping are very helpful for my career. My company supply pipes and fittings to the Oil & Gas, Petrochemical, Refining, Onshore / Offshore and Power Generating industries.

I'm new in this industries and my job is to sell. My main focus are product knowledge, Material specification and Technical specification. I would like to learn as much as I could as I'm not from any engineering background.

Could you kindly advise on my focus and how should I start with?
Your kind assistance will be greatly appreciated.

Many thanks and regards,

Answer from Werner Sölken

Hi Vincent,

Please read question & answer pos. 86 here below

greetings Werner

Question 86: i would like to know how a piping engineering work shall be

Dear Sir,

As I read piping stuff from your website for increase knowledge so, I would like to thank for providing so much stuff on your website.
Apart from this I would like to know How a Piping engineering work shall be proceed step by step to complete a job.

Thank you
Lalit Kumar
(Engineer - Mechanical)

Answer from Werner Sölken

Give me specific questions. Then I'll answer.

greetings Werner

Thank you for revert back. My question is that We are small organization and we are looking to setup Piping Department in our company so that how do a job of Piping or Piping document sequence shall be followed for example: Isometric drawing is prepared after pipe stress analysis ? or Not.
If you further not clear about question then feel free to revert.

Thank you
Lalit Kumar

Answer from Werner Sölken

Of course I can help you.
But I think you can not expect from me that I can set up an organization for you.
First you must have someone who can cope perfectly with eg the CAESAR program, and that person has a lot of experience with the construction or alteration of pipeline systems.
(CAESAR evaluates the responses and structural stresses or piping systems to international codes and standards.)

Your question:
(Isometric drawing is prepared after pipe stress analysis? Or Not.)

A piping designer will make more models ...
Is it a new plant?
Is it a live plant?
Which space do you need?
Which space do you have?
What is the temperature?
What is the pressure?
etc. etc.
thousands of things

What I said, I want to help you, but to set up an organization takes a lot of time and a lot of experience.

greetings Werner

Question 85: difference between caps and dished ends

Good Morning,

Great thanks for all your efforts in this wonderful website. Just I'd know the difference between caps and dished ends (with more technical details)

Ain Naaja Alger

Answer from Werner Sölken

Hi Ain Naaja Alger,

Vessel dished ends are mostly used in storage or pressure vessels. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere while requiring only a slightly thicker wall.

The starting material is first pressed to a radius (1) and then curled at the edge creating the second (2) radius. Vessel dished ends can also be welded together from smaller pieces.

With respect to standard caps:
I can not tell exactly what the difference between a cap and a hemisphere.
If you are patient, I will add the answer to my website...I'll post

greetings Werner

Answer from Werner Sölken

Hi Ain Naaja Alger,

Look on this page:

Manufacturing Butt Weld Fittings Greetings Werner

Question 84: ss 182 f 316l material can withstand subfreezed temp

Dear Werner,

SS 182 F 316L Material can withstand subfreezed temperature upto -425 deg F.
If flange to be designed for Such a low subfreeze temperature then as per ASME B16.5 at particular rating say 900# what will be retainment pressure.
For e.g if PT Table as per ASME B 16.5 for 900 # rating SS 182 F 316 L material gives value -20 to 100 - 1800 Psig then -425 deg F - ? Pressure as Such temperature can come


Answer from Werner Sölken

Hi Prashant,

The ASME B31.1 and ASME B31.3 Codes permit the use of most steel down to -20degF (-29degC).
Below this, certain grades of carbon and nickel steel with good toughness and austenitic stainless steels are needed.
Austenitic stainless steels are extensively used for service down to as low as liquid helium temperature (-269 deg C). This is largely due to the lack of a clearly defined transition from ductile to brittle fracture in impact toughness testing.

Unfortunately I have no data on Pressure-Temperature Ratings below -29 deg C.

greetings Werner

Question 83: what is the difference when sizing a prv based on working

Dear Werner,
What is the difference when sizing a PRV based on Working condition and Standard condition?
Is there a reason why they choose one or the other?

Thanking you in advance for your reply.

Keep up the good work.
Best regards
Steven Ng

Answer from Werner Sölken

Hi Steven,

As an example, Temperature:

Standard version = Working -10°C + 60°C
Low temperature version = Working -20°C + 60°C

greetings Werner

Question 82: what is the different between rating and schedule in piping

Dear Wermac,
Could you please explain what is the different between rating and schedule in piping?

Best Regards,
Vu Tat Tuan (Mr.)
Mechanical Engineer

Answer from Werner Sölken

Hallo, Vu Tat Tuan,

Rating is the pressure rating (Pressure Class), eg Class 150, 300, 600, etc..
Schedule is the wall thickness of, e.g., a pipe, a fitting etc.

greetings Werner

Question 81: your site has been invaluable as a reference

A quick note of thanks for the use of your site. It is certainly the most comprehensive one I have found. I recently arrived on a new natural gas fractionation facility construction site in West Virginia USA. Your site has been invaluable as a reference.


Answer from Werner Sölken

Hi Frank,

Thanks for your compliments on my website.

greetings Werner

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