Questions & Answers

184 - 181 questions

184.. can ring joint gaskets be reused?
183.. dimensions male & female flanges
182.. klopt het dat de afmetingen van DIN flenzen er niet meer in staan..
181.. what is the difference between relief and safety valve..

Question 184.. can ring joint gaskets be reused?

Good day Mr,

In a few weeks we want to hydrostatically test a pipe system, where Ring Typ Joint flanges are used. For a good seal, we want to use the octagonal rings, which are prescribed for the respective flanges. Once the test is done, all the pipe sections will be disassembled, and transported to an external location.

My question is: can we reuse the octagonal rings?

Thank you in advance for your response.
Best regards,
Radu Dragomir

Hi Radu,

Ring type joints are designed to have a limited amount of positive interference, which ensures that the ring type joint seats correctly into the groove on compression. Their reuse is not recommended for two reasons..

  1. The initial seating of the gasket will be impaired.
  2. When the gasket is plastically deformed, work hardening of the external metal surface occurs. This may result in permanent damage to the groove.

Please also check out Gaskets for flanged Connections

greetings Werner


Question 183.. dimensions male & female flanges

Good morning Werner,

I still use your site regularly. Actually, ever since I did an internship at the company where you worked at the time.

At my employer we have a unit where chlorine is processed and male female flanges are used. The problem is that I can only find very little information regarding measurements, not even in the VOMI fitters booklet.

Do you see an opportunity to add it to the site if you could get the information? This would be of great help to me and other colleagues.

Yours sincerely,
Mike Oskam

Hi Mike,

Thanks for the interest in my website.

On Male-Female and Tongue & Groove you will find my answer.

The overall dimensions of the Male and Female flanges correspond to the standard dimensions according to ASME b16.5, so I have not added those dimensions either.

The length of the stud bolts is either the same or slightly shorter.

I'm still going to see if it's necessary to add the Stud Bolt lengths.

Gr, Werner


Question 182.. klopt het dat de afmetingen van DIN flenzen er niet meer in staan..

Goedendag heer Sölkers,
Wij kennen elkaar niet persoonlijk, maar ik ken u van de enorm nuttige website, die ik bijna dagelijks gebruik.
Klopt het dat de afmetingen van DIN flenzen er niet meer in staan?
Ik werk bij een oude plant die oorspronkelijk gebouwd is volgens de DSM-standaarden, dus NEN-DIN. Maar nu kan ik op de website de DIN specificaties niet meer terugvinden, en dat is niet handig. Inmiddels zijn de huidige standards en pipespecs wel allemaal gewijzigd naar ASME/ANSI, maar we hebben nog veel te maken met de geschiedenis van de fabriek.

Willem Zuyderduyn
Piping engineer

Hallo Willem,

Artikelen over DIN vindt je inderdaad niet meer in het hoofdmenu DIN. Om allerlei redenen heb ik DIN naar het menu 'SOCIETIES' verplaatst. (Welding Neck Flange Type 11 PN10-PN400) . DIN is dus nog steeds 'aanwezig'. Overigens heb ik ook voor een 'oude' plant de BS 3293:1960 British Standard toegevoegd. Deze flens afmetingen kwam ik kort geleden nog tegen, en de gegevens daarover waren nihil. Deze link brengt je naar de norm BS 3293:1960

Gr, Werner


Question 181.. what is the difference between relief and safety valve..

Dear Werner Solken,

For my study I have to answer the question 'what is the difference between relief and safety valve?. Can you give me a little help please.

Thank you in advance.
Kind Regards,
Anil Patel

Hi Anil Patel,

Relief or Safety valves perform the following basic functions.

They protect a system against excessive pressure or sudden increases in pressure. When the pressure in a line reaches a pre-set high pressure, the valve opens and allows the pressure to escape either to atmosphere or to another part of the system. Safety valves are generally used for steam, air or other gases. Relief valves are usually used for liquids.

Relief valves versus Safety valves
Relief Valve Safety Valve
Purpose is to limit pressure to a specific pressure. Fail-safe purpose, protect people, property and environment.
Opens proportional to the pressure increase. Starts opening before the set pressure and pops open at the setpoint or at a defined point.
Opens when the pressure reaches a set pressure limit. Starts opening before the set pressure limit.
Can not be used at maximal overpressure values of 3% maximum allowable operating pressure (MAWP) Can be used at maximal overpressure values of 3% MAWP
Relief Valve
Relief Valve
Safety Valve
Safety Valve

greetings Werner


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