Question and Answer 111-120

Question 120: Is there any formula/method to calculate the thickness of...?

Dear werner,
1) I have one question that Is there any formula/method to calculate the thickness of pipe for a respective schedule number without the use of schedule chart.
For Eg: 6" CS Pipe Sch 80 what is thickness? to know without using chart, is it possible. If not how did this schedule chart was framed at the initial stage.

Mahather Mohamed H.

Answer from Werner Sölken

Hi Mohamed
Yes, there are formulas, with which you can calculate the wall thickness of a pipe, fitting, etc..
My advice: use the standards ASME, DIN, JIS, BS (i), etc.

greetings Werner

Question 119: can i connect two prv outlet together?

Can you help me for PRV connectiong piping for 2 nos of pressure vessels?

PRV outlet

Pradip B. Mahadik

Answer from Werner Sölken

Hi Pradip,
Yes you can connect multiple pressure relief valves on a header, but note...

Pressure relief valves on clean non-toxic, non-corrosive systems may be vented directly to atmosphere.
Pressure relief valves on corrosive, toxic or valuable recoverable fluids are vented into closed systems.
Valves that vent to the atmosphere, either directly or through short vent stacks, are not subjected to elevated back pressure conditions. For valves installed in a closed system, or when a long vent pipe is used, there is a possibility of developing high back pressure. The back pressure on a pressure relief valve must always be evaluated and its effect on valve performance and relieving capacity must be considered.

If pressure in the valve outlet varies while the valve is closed, the valve set pressure will change. If back pressure varies while the valve is open and flowing, valve lift and flow rate through the valve can be affected. Care must be taken in the design and application of pressure relief valves to compensate for these variations.

greetings Werner

Question 118: what are chopper valves?

Good Day Werner,
Curious if you had any information regarding Chopper Valve's?
I'm not familiar with them nor did I know they existed. :)

Best Regards,
Jordan G. Gann

Answer from Werner Sölken

Hi Jordan,
I have no idea what type of valve it is.
Perhaps it has something to do with motorcycles, I do not know.

greetings Werner

Question 117: do you have standard dimensions for flangeolets?

I'm trying to find center line lengths of flangeolets and have hit a brick wall! Do you have them or are there no standard dimensions for flangeolets?

Gary Amass

Answer from Werner Sölken

Hi Gary,

What is a standard length?
What is the diameter of the header?
What is the thickness of the insulation?
There is no standard for Weldoflanges, but I suspect the link below can help you further.

Promat BD is one of the largest suppliers of flanged products

greetings Werner

Question 116: information about a steam turbines

HELLO Mr.Werner Solken

i'm really impressed about your website and i have found a lot of information which adds a lot into my brain since i have just finished my studies and i joined a Petrochemical plant in Oman.

My designation as Mechanical Engineer...I would like you plz if you give me information about a steam turbines..I will be so pleased if you a lert me in this subject..

with my best regards

Answer from Werner Sölken


My knowledge of steam turbines is not enough, to answer your request / question.

The .pdf document from Energy and Environmental Analysis probably gives you some answers on your question.

greetings Werner

Question 115: suitable material of restrictive orifice plate within process as...

Dear Sir/Madam,

I've a modification of upgrading metering station and there is need to install a restriction orifice plate which is I don't really familiar with the suite materials for design piping. So, I hope that you can assist me to chose suitable material of restrictive orifice plate within process as below:

  1. Inlet Pressure ( min/max) - 20/23 barg
  2. Outlet Pressure (min/max) - 15/17 barg
  3. Flow Rate (min/max) - 0/24 mmscfd

Hope to hear from you soon and please do revert to us in ASAP.

Best Regards
Muktarrudin B. Ismail Kari

Answer from Werner Sölken


The calculation of an orifice can be a very complex issue. Use the AGA Report Number 3 (API 14.3) for industrial standard specifications on orifice measurement, either gas or liquid, single phase.


Get a copy of Crane technical paper 410. It is an invaluable resource and covers how to calculate the resistance created by an orifice in a piping system.

greetings Werner

Question 114: where or which document we can find the dimensional parameters or dimensions for API valves of 10000 rating or greater?

Hi Werner,

hope you will be doing great, i have a query relating to API standards, i want to know from where or which document we can find the dimensional parameters or dimensions for API valves of 10000 rating or greater because API 6D covers up to 2500 ratings valves.
Kindly share you knowledge. thanks

UMAIR AHMED Piping / Stress Engineer

Answer from Werner Sölken


API Spec 6A

The document is applicable to the following specific equipment:

  • wellhead equipment (casing head housings, casing head spools, tubing head spools, cross-over spools, multi-stage head housings and spools)
  • connectors and fittings (cross-over connectors, tubing head adapters, top connectors, tees and crosses, fluid-sampling devices, adapter and spacer spools)
  • casing and tubing hangers (mandrel hangers, slip hangers)
  • valves and chokes (single valves, multiple valves, actuated valves, valves prepared for actuators, check valves, chokes, surface and underwater safety valves and actuators, back-pressure valves)
  • loose connectors (weld neck connectors, blind connectors, threaded connectors, adapter and spacer connectors, bullplugs, valve-removal plugs)
  • and other equipment (actuators, hubs, pressure boundary penetrations, ring gaskets, running and testing tools, wear bushings)

greetings Werner

Question 113: why pwht is not required for welding stainless steels?

Dear Mr. Werner Sölken,

I really pleased to see your website and you are doing really good job.
can be please clarify me following questions,

  1. Why PWHT is not required for welding stainless steels?
  2. What is difference between Duplex and Superduplex stainless steel?
  3. Can I weld duplex or superduplex stainless steel to carbon steel and, if so, what consumable should I use?

Waiting for your reply.
V. Meenakshi Sundaram,
QC Engineer,

Answer from Werner Sölken


  1. Austenitic steels are not susceptible to hydrogen cracking, therefore pre-heating is seldom required, except to reduce the risk of shrinkage stresses in thick sections. Post weld heat treatment is seldom required as this material as a high resistance to brittle fracture; occasionally stress relief is carried out to reduce the risk of stress corrosion cracking, however this is likely to cause sensitisation unless a stabilised grade is used.
  2. The difference between Duplex and Super Duplex is the so called PREN values (Pitting Resistance Equivalent Number) which for Super Duplex should be considerably higher. So this material has better properties against pitting corrosion compared to standard Duplex Stainless Steel. PREN is also called PI (Pitting Index) in some specifications.
    Shortly, Super duplex is simply a stronger, sturdier form of Duplex. Where you would use Duplex you can generally also use Super Duplex.
  3. Duplex and superduplex stainless steels may be welded to carbon steels using one of a range of consumable types. When selecting the most appropriate consumable, the need to have weld metal strength overmatching with respect to the lower strength of the two parent steels should be considered.
    The highest weld metal strength probably will be achieved with the use of a superduplex consumable. Alternatively, where such high strength is not required, a 22%Cr duplex stainless steel filler, a nickel-based filler or a 309 type austenitic stainless steel may be used.

I hope that your questions are answered.

greetings Werner

Dear Mr. Werner Sölken,

Thanks for your kind reply.
And i will be back to you shortly.

V. Meenakshi Sundaram,
QC Engineer

Question 112: is it possible to fix the spectacle blinds with any standard flange same size...

Dear Sirs

We are Engineering company, we need your kind advise for following:
Ref. your attached dimensions table for Spectacle blinds thickness and pipe size diameters and Rating, our Questions:

  1. Is it possible to fix the Spectacle blinds with any Standard Flange same size and Rating?
  2. For the thickness of Spectacle blind shown are the Max. thickness allowable thickness? i.e. the thickness of Spectacle blind under 6.0", 150 RF. is 12.7mm , is it possible to fix a Spectacle blind of (12.7 mm + 5 or 8 mm)?
  3. Is there a solution/tool to be used to provide more distance between the flanges faces in order to provide more space/clearance to insert thicker Spectacle blinds?

Appreciate your kind Technical advise
Thank you
Best Regards
Ndeem Shaker

Answer from Werner Sölken


  1. Yes, it is possible to fix the Spectacle blinds with any Standard Flange same size and rating.
  2. I do not know why you want to apply a thicker plate, but yes it can.
  3. Mounting of a thin plate, generally succeed it. A standard Spectacle or even thicker, it is usually a problem.
    If during the design of the pipeline no Spectacle is included, it is almost impossible to open a flange connection wide enough.

greetings Werner

Question 111: i am looking for a 2.5in socket weld half coupling


I am looking at the socket half coupling and have a question about how to understand the Socket Bore Measurement. I am looking for a 2.5" diameter.

Andy Jones

Answer from Werner Sölken


What is your question about Socket Bore Measurement?

Below are the dimensions of Socket Weld Half Couplings acc. to ASME B16.11

Dimensions of Socket Weld Half Couplings


  1. Upper and lower values for each size are the respective maximum and minimum dimensions.
  2. Average of socket wall thickness around periphery shall be no less than listed values. The minimum values are permittedin localized areas.

greetings Werner

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