API MPMS 17.4-2016 pdf download.Manual of Petroleum Measurement Standards Chapter 17.4 Method for Quantification of Small Volumes on Marine Vessels (OBQ/ROB).
1 Scope This standard applies only to quantification by manual gauging of small volumes on marine vessels prior to loading or upon completion of discharge. It does not address clingage, hydrocarbon vapors, cargoes in transit, or cargo pumpability. Refer to API Manual of Petroleum Measurement Standards (MPMS) Chapter 3. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. API MPMS Chapter 3 (all relevant sections), Tank Gauging API MPMS Chapter 3.1 A, Standard Practice for the Manual Gauging of Petroleum and Petroleum Products API MPMS Chapter 7, Temperature Determination API MPMS Chapter 8.1 , Manual Sampling of Petroleum and Petroleum Products API MPMS Chapter 1 2.1 .1 , Calculation of Static Petroleum Quantities—Upright Cylindrical Tanks and Marine Vessels API MPMS Chapter 1 7.1 , Guidelines for Marine Inspection API MPMS Chapter 1 7.2, Measurement of Cargoes On Board Tank Vessels API MPMS Chapter 1 7.1 1 , Measurement and Sampling of Cargoes On Board Tank Vessels Using Closed and Restricted Equipment 3 Terms and Definitions For the purposes of this standard, the following terms and definitions apply. Other terms used in this standard are defined in API MPMS Chapter 1 or other API petroleum-measurement standards. 3.1 clingage Cargo that adheres to all surfaces of the emptied portion of the tank other than bottom surfaces. 3.2 liquid volume The measurable amount of material that is free-flowing at the time of measurement. 3.3 multipoint gauging The activity of measuring cargo in a vessel tank through two or more openings in the top of the tank.
3.4 nonliquid volume The measurable amount of material that is not free-flowing at the time of measurement. Nonliquid material may include any one or a combination of hydrocarbon waxes, water/oil emulsions, sediment, or solidified cargo. 3.5 on board quantity OBQ The material in a vessel’s cargo tanks and piping before the cargo is loaded. 3.6 remaining on board ROB The material remaining in a vessel’s cargo tanks and piping after the cargo is discharged. 3.7 sediment Solid materials including, but not limited to, sand, rust, and scale. 3.8 slops Oil, oil/water/sediment, and emulsions contained in slop tanks or designated cargo tanks. The mixture usually results from tank stripping, tank washing, or dirty ballast phase separation. 3.9 sludge That element of the material in a ship’s cargo tank that is essentially not free-flowing. Sludge consists of hydrocarbon waxes and may contain water/oil emulsions and sediment. The use of this term is not recommended. 3.10 wedge formula A mathematical means to approximate small quantities of measurable liquid and/or nonliquid material on board that is in a wedge configuration and does not touch all bulkheads of the vessel’s tank. The formula is based on cargo compartment characteristics, vessel trim, and the depth of the material. 3.11 wedge table A vessel’s cargo tank volume table calculated on the wedge formula for use when cargo does not touch all bulkheads of the tanks. Wedge tables preclude the need for calculation by wedge formula at times of cargo transfer. 4 Safety and Health Considerations 4.1 General Personnel involved with the gauging and sampling of petroleum and petroleum-related substances should be familiar with their physical and chemical characteristics, including potential for fire, explosion, and reactivity, and with the appropriate emergency procedures as well as potential toxicity and health hazards.
4.2 Static Electricity Hazards If the tank is in a noninert condition, specific precautions will be required with regard to safe measurement and sampling procedures when handling static accumulator oils. These are generally as follows: during loading, and for 30 minutes after the completion of loading, metallic equipment for dipping (gauging), ullaging, or sampling shall not be introduced into or remain in the tank. Examples of equipment include manual steel ullage tapes, portable gauging devices mounted on deck stand pipes, metal sampling apparatus, and metal sounding rods.