API STD 2000:2014 pdf download

API STD 2000:2014 pdf download.Venting Atmospheric and Low-pressure Storage Tanks.
2.6
full open position
Position where lift of the pallet is sufficient for the nozzle to control the flow or where the pallet or main valve seat lifts against a fixed stop.
2.7
nonrefrigerated tank
Container that stores material in a liquid state without the aid of refrigeration, either by evaporation of the tank contents or by a circulating refrigeration system.
NOTE Generally, the storage temperature is close to, or higher than, ambient temperature.
2.8
normal cubic meters per hour
Nm3/h
SI unit for volumetric flow rate of air or gas at a temperature of 0 °C and pressure of 101.3 kPa, expressed in cubic meters per hour.
2.9
normal venting
Venting required because of operational requirements or atmospheric changes.
2.10
overpressure
Pressure increase at the PV valve inlet above the set pressure, when the PV valve is relieving.
NOTE 1 Overpressure is expressed in pressure units or as a percentage of the set pressure.
NOTE 2 The value or magnitude of the overpressure is equal to the value or magnitude of the accumulation when the valve is set at the maximum allowable working pressure or design pressure and the inlet piping losses are zero.
petroleum
Crude oil.
2.12
petroleum products
Hydrocarbon materials or other products derived from crude oil.
2.13
PV valve
Weight-loaded, pilot-operated, or spring-loaded pressure vacuum valve used to relieve excess pressure
and/or vacuum that has developed in a tank.
2.14
rated relieving capacity
Flow capacity of a relief device expressed in terms of air flow at standard or normal conditions at a designated pressure or vacuum.
NOTE Rated relieving capacity is expressed in SCFH or Nm3/h.
2.15
refrigerated tank
Container that stores liquid at a temperature below atmospheric temperature with or without the aid of refrigeration, either by evaporation of the tank contents or by a circulating refrigeration system.
2.16
relief device
Device used to relieve excess pressure and/or vacuum that has developed in a tank.
2.17
relieving pressure
Pressure at the inlet of a relief device when the fluid is flowing at the required relieving capacity.
2.18
required flow capacity
Flow through a relief device required to prevent excessive pressure or vacuum in a tank under the most severe operating or emergency conditions.
2.19
rollover
Uncontrolled mass movement of stored liquid, correcting an unstable state of stratified liquids of different densities and resulting in a significant evolution of product vapor.
2.20
set pressure
Gauge pressure at the relief device inlet at which the device is set to start opening under service conditions.
2.21
standard cubic feet per hour
SCFH
USC unit for volumetric flow rate of air or gas (same as free air or free gas) at a temperature of 15.6 °C
(60 °F) and an absolute pressure of 101.3 kPa (14.7 psi), expressed in cubic feet per hour.
2.22
thermal inbreathing
Movement of air or blanketing gas into a tank when vapors in the tank contract or condense as a result of weather changes (e.g. a decrease in atmospheric temperature).
2.23
thermal out-breathing
movement of vapors out of a tank when vapors in the tank expand and/or liquid in the tank vaporizes as a result of weather changes (e.g. an increase in atmospheric temperature).
2.24
vapor pressure
The pressure exerted when a liquid is in equilibrium with its own vapor. Vapor pressure is a function of the substance and temperature.
2.25
wetted area
Surface area of a tank exposed to liquid on the interior and heat from a fire on the exterior.
3 Nonrefrigerated Aboveground Tanks
3.1 General
Section 4 covers the causes of overpressure or vacuum; determination of venting requirements; means of venting; and selection and installation of venting devices.