API STD 6DX:2012 pdf free download.Standard for Actuator Sizing and Mounting Kits for Pipeline Valves
8.1.3 Safety factor and operating time
The following data shall be provided by the purchaser, for both opening and closing directions:
a) minimum and maximum operating time;
b) actuator sizing safety factor at 8.1.2 a), c) and d).
8.1.4 Valve dimensions
The valve manufacturer/supplier shall provide all relevant valve dimensions, including but not limited to the following:
a) stem dimensions;
b) stem thread form, pitch, lead, whether right-hand or left-hand and number of starts;
c) dimensions of stem key;
d) mounting pattern (top works) dimensions.
8.1.5 Electric actuator data
For electric actuators, the following data shall be provided by the purchaser:
a) voltage, phase, frequency;
b) voltage variation and frequency variation;
c) number of consecutive valve strokes;
d) number of starts per hour;
e) minimum and maximum operating and ambient temperatures;
f) actuator configuration (single- or double-acting);
g) action on loss of supply energy (close, open or last);
h) number of strokes from stored-power source.
8.1.6 Pneumatic/hydraulic actuator data
For pneumatic and hydraulic actuators, the following data shall be provided by the purchaser:
a) fluid type, cleanliness and, where applicable, gas composition;
b) minimum and maximum supply pressure;
c) minimum and maximum operating and ambient temperatures;
d) actuator configuration (single- or double-acting);
e) action on loss of supply energy (close, open or last);
f) number of strokes from stored-pressure source, if applicable.
Stroke damping may be required to control operating speed.
Maximum supply pressure, by agreement, may be regulated by the manufacturer or supplier for the purpose of meeting sizing requirements (in doing so, it becomes the maximum operating pressure, which shall be less than or equal to the maximum rated pressure).
8.2 Sizing method
The valve torque/thrust values and other related data shall be determined as described in 8.1.
The actuator shall be selected based on minimum supply voltage or minimum supply pressure, maximum compressed spring force and other related data as described in 8.1.
Actuator maximum output torque/thrust based on the maximum supply voltage or operating pressure shall not exceed the valve MAST at any point of travel. For pneumatic/hydraulic actuators, when the maximum supply pressure is reduced by means of a regulator and relief valve system, then the pressure used to
establish the maximum output torque/thrust shall be based on the relief valve set pressure. For electric actuators, when torque/thrust-limiting devices are active, the maximum torque/thrust shall be based on the rated torque/thrust setting unless otherwise agreed.
9 Instrumentation/regulation
9.1 Torque limiting settings — Electric actuators
The maximum output torque shall not exceed the valve MAST.
Torque-limiting devices shall not be bypassed unless otherwise agreed.
9.2 Torque/thrust limiting controls — Pneumatic/hydraulic actuators If the output of a pneumatic or hydraulic actuator has the potential to exceed the valve MAST, a regulator shall be used along with a safety relief valve. The torque/thrust output at the relief valve set pressure shall be less than the valve MAST.
NOTE Typically, the minimum relief valve set pressure is either 110 % of regulator set pressure or +50 kPa [+0,5 bar; +7.3 psi)]. Alternative means of limiting supply pressure may be offered by agreement.
10 Materials
10.1 Material specification Specifications for metallic pressure-containing parts shall be issued by the anufacturer and shall address, as a minimum, the following:
a) material type and grade (e.g. carbon steel, austenitic stainless steel, ferritic ductile iron, non-ferrous alloys, etc.);
b) product form;
c) chemical composition;
d) condition/heat treatment;
e) mechanical properties;
f) Charpy impacts, if applicable;
g) type of inspection document in accordance with ISO 10474 or EN 10204.
10.2 Service compatibility
All parts, metallic and non-metallic, in contact with the operating fluids and lubricants shall be suitable for the commissioning fluids and service specified by the purchaser. Metallic materials shall be selected in such a manner as to avoid corrosion and galling which can impair function and/or pressure-containing capability.API STD 6DX pdf download.API STD 6DX:2012 pdf free download
