API 2350: Overfill Prevention for Storage Tanks in Petroleum Facilities Flashcards
What is the scope of this document? (API 2350-12, Section 1.1)
The scope of this standard is intended for the overfill protection for storage tanks associated with marketing, refining, pipeline and terminals containing Class I or Class II petroleum liquids. Use is recommended for Class III petroleum liquids.
What is a “high-high tank alarm?” (API 2350-12, Section 3.22)
An alarm generated when the product level reaches the high-high tank level.
What is a “critical high level?” (API 2350-12, Section 3.13)
The highest level in the tank that product can reach without detrimental impacts (i.e. product overflow or tank damage) (see 4.4.2.1).
What is an “independent alarm”? (API 2350-12, Section 3.25)
An alarm function separate from the device or system used for routine operational tank level measurement.
What is the “maximum working level” for a tank? (API 2350-12, Section 3.31)
An operational level that is the highest product level to which the tank may routinely be filled during normal operations (see 4.4.2.3).
At what type of facility are level detectors not required? (API 2350-12, Section 4.4.5.2)
Category 1
How must product transfer be monitored for tanks in fully automated operation at an unattended facility? (API 2350-12, Section 4.4.5.4.4)
Tanks in fully automated operation at unattended facilities shall be equipped with an independent LAHH sensor that shall activate an alarm with the transporter to initiate termination procedures or shall automatically terminate the flow to the tank. These systems shall also initiate receipt termination procedures in the event of a power failure in the level measuring system based on an appropriate response time (4.4.2.5).
How does a high-high tank alarm accomplish overfill protection? (API 2350-12, Section 5.1.2.1)
The high-high alarm (initial alarm at the high-high tank LOC) requires that operating personnel from the responsible owner and operator and transporter shall take previously defined and agreed action to terminate the receipt.
What is the AOPS level, and how is it determined? (API 2350-12, Section 4.4.2.4)
The AOPS level is an emergency action level set sufficiently below the critical high level to enable automatic termination of a receipt before the critical high level is reached.
The vertical distance in the tank between the critical high level and the AOPS level is calculated based on the response time required by the automated system to terminate a receipt at the maximum flow rate specific to the tank under consideration. At a minimum, the distance between the critical high level and the AOPS level shall not be less than 3 inches to account for potential errors in data and measurements.
What should be the criteria for determining the point at which the high-high tank level detector is located? (API 2350-12, Section 4.4.2.2)
The vertical distance in the tank between the critical high level and the high-high tank level is calculated based on the response times required to terminate a receipt at the maximum flow rate specific to the tank under consideration.
What four functions must an AOPS perform when product in the tank has reached the AOPS level? (API 2350-12, Section 5.5)
1) change appropriate valve(s) to the safe open (closed) state(s) at the agreed-upon valve travel speed(s); if the valve is being opened (closed) remotely when the AOPS sensor signal is received, the valve shall immediately start moving to the safe state at the predetermined rate;
2) inhibit movement of the valve(s) from the safe position until the system has been reset from the local alarm and signal control panel, the site has become attended, and operating procedures for abnormal conditions have been implemented;
3) in case of power failure procedures shall be in place to promptly terminate receipt under manual control; and
4) the AOPS valves shall not be operated manually unless specific procedures are used which require manual operation of the valve to address reducing the high liquid level.
How often should system electronic integrity tests be conducted at unattended facilities to ensure proper operation of the tank level alarm system? (API 2350-12, Section 4.5.4.2)
Within 24 hours before every receipt, at least weekly
What type of liquid level detectors are used in cone roof tanks? (API 2350-12, Table C. 1)
Float point mechanical sensors
What are three minimum levels of concern that must be established for each tank? (API 2350-12, Section 4.4.2)
1) critical high level (CH)
2) high-high level (HH), and
3) maximum working level (MW)
What is the minimum distance between the critical high level and the high-high tank level? (API 2350-12, Section 4.4.2.2.2)
3 inches
