SPRING DESIGN CALCULATIONS FOR SAFETY VALVE 2

[skengg]

hello to all,
this is bit beginner question but i want to know the design calculations of spring for choosing any particular safety valve application.
calculation in such a way that also gives me data of spring range we can use for maximum and minimum pressure in safety valve.
there are several articles available but mostly do not give clear images regarding in safety valve point of view.
can anybody suggest any book or literature regarding this.

 

[The Obturator]

1. Each Pressure-relief Valve manufacturer has a set of spring tables for each size/type/pressure rating of valve they produce. These tables are then by spring material and corresponding alternative material requirements (eg. Spring x123 in Chrome Steel = Spring X456 in Inconel X750 - same pressure range).
2. A typical conventional valve say a 2 x H x 3 / 150 x 150 may have some 30 springs or more, to cover the pressure range of this size/rating (which would be 15 to 285 PSIG). Each of these springs has its own pressure range (15 to 25 PSIG, 100 - 115 PSIG etc.).
3. All spring are designed by the manufacturer and proven with their spring vendor.
4. Spring designs follow the manufacturers design and must also meet the requirements in ASME XIII (2021) and/or applicable standard required.
5. Each manufacturer has unique designs which are not interchangeable with other manufacturers.
6. Manufacturers designs are confidential information.


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[skengg]

thanks the obturator for replying,
i know its based on manufacturer design, but generally i want to read some literature regarding spring design for safety valve, i know basic calculation for spring design but as per safety valve forces and pressure need to know how we can select spring for particular pressure range.

 

[The Obturator]

Such a publication only exists with manufacturers and kept confidential to them. You need to establish dialogue with a spring manufacturer and draw up your own specification that meets ASME standards. To start, you need to be drawing up specs that indicate the outside and internal diameter of spring, its free length, tension (pressure), how the spring ends are finished (% flat), preferred material, valve minimum lift etc., etc.


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[The Obturator]

FYI. There is an out of print book 'Valve Design by G. H, Pearson' which is referenced often in this forum. It was last published in 1979. Many valve design engineers have taken the basics of this publication to make new designs. It does have a section on safety valves, and particularly spring design for safety valves - the references are out of date British specifications, but the principle is there. The original 1953 edition of this book can sometimes be found online, but the quality is not great. I attach the safety valve spring design relevant pages from the 1953 edition as it is well out of print and copyright (note that the quarter diameter referred to means the safety valve nozzle bore/4 = D/4 which is used today for so called full lift valves).


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[skengg]

thanks the obturator for giving information