Why does ASME VIII Require Lifting Levers? 1

[Fac_Eng]

As many of us are aware, ASME Sec VIII Div 1 UG-136(a)(3) requires relief valves in air, water exceeding 140°F (60°C), and steam service to have a lifting lever. My question is does anyone know why these specific services require a lifting lever but not others?

I am aware of code case 2203, in this instance I am just wondering what the underlying concern was to warrant this clause.

Thanks!

 

[The Obturator]

The requirement of lifting levers on pressure relief valves, is required to allow the operator to regularly manually open the PRV in order to maintain the internals functionality. Water that contained impurities in days of old, had a tendency to stick the moving parts with the residue from steam generation The rule applied to air receivers and later on hot water when the ASME Code added liquid service in the 80's. With other applications it was not a requirement. Generally PRV's in refinery, petrochemical service would not have levers as operators did not want to exhaust toxic fluids. Most certainly steam and air duty PRV's were the original 'Safety Valves' with pop opening action fitted with levers as standard.

I should also add that levers are only mandatory if the 'NB/UV' Stamp is a PRV requirement, unless Code Case 2203 is applied by the user as you noted.

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[Dhurjati Sen]

One line in addition to what The Obturator Sir has said.

Maintenance guys also use these levers for steam valves during floatation or pop tests, just to ensure the correct set pressure.

DHURJATI SEN