Hydrotest Pressure Vs Design Pressure.

Design pressure is usually the pressure set by process engineer, based on the results of a simulation or similar study. Hydrotest pressure is the actual pressure the vessel is tested at. Usually the hydrotest pressure is 1.3 times the design pressure (ASME requirement). 


So if the design pressure is 100 KPa(g), the hydrotest pressure would be 130 KPa(g). Therefore the rule (or requirement) is called 10/13 rule.

Maximum allowable Working pressure (MAWP) Vs Design pressure

Design pressure is usually the pressure set by process engineer, based on the results of a simulation or similar study. MAWP is the pressure based on the actual characteristics of the vessel/equipment (which is usually manufactured to exceed the specifications set by process engineer).

Maximum allowable working pressure is always greater than or equal to design pressure.

SWPF - Acronym

In upgrader/refinery/petrochemical/chemical plant terms,

SWPF is site wide power failure.

Cooling water tube velocity in coolers

The usual recommended range is 0.3 to 2.4 m/s. A velocity of 1.5 m/s is good. Maximum is 3m/s

Chemical process engineering - cooling water piping velocity:

Is it better to put new tires on the front or back?

The new tires should be on the rear of the vehicle.

Read more here.

What is FLA for a motor

Full Load amps


FLA is the nameplate amperage rating of the motor when it is running at its designed horsepower and on the motors designed voltage. 746 watts = 1 HP. The FLA of a 1 HP motor at 240 volts would be W = amps x volts, Amps = Watts/Voltage. 746/240 = 3.1 amps full load. Overload the motor and the amps go higher, motor running at no load amps are lower than FLA

Action of flow controllers, temperature controllers, level controllers and pressure controllers.

For level and pressure controllers where outlet flow is controlled, the controller OP will increase with increasing PV.

• For fail safe close valves (Air to open) like level controllers, the controller is direct acting
• For fail safe open valves (Air to close) like pressure controllers, the controller is reverse acting

For level and pressure controllers where inlet flow is controlled, the controller OP will decrease with increasing PV.

• For fail safe close valves (Air to open) like level controllers, the controller is reverse acting
• For fail safe open valves (Air to close) like pressure controllers, the controller is direct acting

For flow controllers, the controller OP will decrease with increasing PV (same as the case of level/pressure controller where inlet flow is controlled).

• For fail safe close valves (Air to open) like level controllers, the controller is reverse acting
• For fail safe open valves (Air to close) like pressure controllers, the controller is direct acting