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TERMINAL OPERATIONS FOR. CRUDE OIL EXPORTS. TERMINAL FUNCTIONS. RECEIVE OIL STORE OIL DEHYDRATE MEASURE EXPORT DOCUMENT. THE GAUGER. THE GAUGER IS ONE WHO: Measures Samples And tests the crude oil to determine; Quantity Quality
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TERMINAL OPERATIONSFOR CRUDE OIL EXPORTS
TERMINAL FUNCTIONS • RECEIVE OIL • STORE OIL • DEHYDRATE • MEASURE • EXPORT • DOCUMENT
THE GAUGER • THE GAUGER IS ONE WHO: • Measures • Samples • And tests the crude oil to determine; • Quantity • Quality • This man/woman’s operations as a crude oil inspector are known to the industry as GAUGING
THE GAUGER’S RESPONSIBILITIES • The Gauger’s Responsibilities Includes: • Gauging (measuring the depth of oil in the tank) • Taking tank temperature • Sampling and testing for BS & W • Checking BS & W on the tank bottom • Checking the tank bottom for free water • General inspection of the tank and /or tank battery • Locking and sealing valves
EFFECT OF WATER ON CRUDE OIL SAMPLE • The API gravity/ density varies with variation in the water content of the crude • The higher the water content, the lower the API gravity.
STORAGE TANKS FUNCTIONS • Collection point for several field production • Distribution point to various end user points • Helps in the planning of production and distribution times • Eliminate overloading certain points • Pipelines and pump capacities can be precisely calculated • A centre of quality control • Serves as last stage of series treatment in the field
TANK TYPES • There are basically two types of tank in the terminal viz: the fixed roof tank and the floating roof tank.
FLOATING ROOF SUPPORT • Feet During Normal Functioning • Feet For Maintenance Operations • Release Valve.
Base Shell Roof Breather Valve Level Indicator Measuring Hatch Inlet Nozzle Outlet Nozzle Manhole Bottom Drain Access Stairway Temperature Indicator Grounding FIXED ROOF TANK
Horizontal Gasket Flexible Metallic Ring Pantograph Collector Rubber Gasket Floating Roof. TANK ACCESSORIES:
RECORDS FOR AUTOMATIC SAMPLING • Sample reference number • Identification of shipment or transfer • Crude type • Date and commencement of sampling. • Date and time of end of sampling. • Nominated quantity • Maximum expected flow rate • Sample grab size, sample rate and calculated sample volume. • The data logged determine: 1 Validity of sample collected 2 Performance efficiency of sampler
CRUDE OIL MEASUREMENTS METHODS • STATIC MEASUREMENT • DYNAMIC MEASUREMENT
ESSENTIAL EQUIPMENT AND FACILITIES FOR STATIC MEASUREMENT • Steel gauging tapes equipped with innage gauging bobs as specified in API 2545.However, for special purpose vessels (SPVs) the ullage gauging method shall be applicable. • Approved calibration table for each tank • Manual sampling cans as specified in ASTM D4057 (Manual of Petroleum Measurement Standards chapter 8- section 1) • Automatic sampling device designed and installed in accordance with ASTMD4117 (Manual of Petroleum Measurement Standards Chapter 8 – Section 2)
ASTM type thermometers of suitable range with accuracy of +/-0.5of and graduation of 1oF(other specifications as in API 2545 or ASTMD1085) Tank to be equipped with a gauge hatch from the roof to the datum plate. Gauge hatch reference point on tank roof to be provided with or adverse weather protection. Gauge hatch with a well illuminated shelter. Side gauge to show depth of liquid in tank, or any suitable arrangement for either local or remote reading of tank liquid levels. ESSENTIAL EQUIPMENT CONT...
API standard 2545 or D1085- “Method of gauging petroleum and petroleum products.” API standard 2543 or ASTM1086- “Method of measuring the temperature of petroleum and petroleum products” ASTM D$057- Manual sampling of petroleum and petroleum products” ASTM D4177- Automatic sampling of petroleum and petroleum products. APPLICABLE STANDARDS
STATIC MEASUREMENT TANK DIPPING (GAUGING) • Innage methods • Outage or ullage method INSTRUMENTS FOR DIRECT LIQUID DETERMINATION • Steel tape or dipstick • Sideglass or gauge glass • Cable and float • Displacement level sensor
INDIRECT INFERENCE LIQUID LEVEL • Radiation absorption gauges • Differential pressure gauges • Hydrostatic pressure gauges • Float or pointer method • For custody transfer and calculation of royalty, manual dipping.
INNAGE GAUGING PROCEDURE • Note: Turn Mixers off, allow liquid sufficient time following any mixing, filling and /or withdrawal operation. Verify tapes not kinked,bobtip or eyelet not appreciably worn. • Clean the tape and /or bob as required. • Apply a thin coat of oil or water indicating paste to tape and/or bob. • Lower tape through gauge hatch and in contact with it . • Lowering not too fast, a distinct strike to be observed. • If no clean observed, strike with three attempts, use alternate innage method. • Read tape to the nearest 1/8’’ and compare with reference height for the tank.
INNAGE GAUGING CONTINUES • If tape reading does not agree, reinitiate starting with two above. • Hold tape and bob in gauging position long enough if oil and/or water indicating paste is used. • Read tape to the nearest 1/8’’ at the colour change on paste. Record the reading(s). With liquid gauging repeat steps 2 to 7 until two readings agree. • Clean tape. • Report average of liquid gauge on the measurement ticket or other accounting document.
ALTERNATE INNAGE METHOD • Procedure applicable for a tank having an innage gauge table. • Use innage gauge tape and bob • There must be good mixing, sufficient time to become still except for month end inventory • Verify tape and bob for kink and worn. With more than 1/16” do not use. • For a new tape verify with an NBS certified tape before use. Clean tape and bob. • Apply a thick coat of oil/or water indicating paste.
ALTERNATE INNAGE METHOD CONTINUES.... • With tape in contact with edge of the gauge hatch, lower tape and bob until bob is immersed in the liquid, with indication of the reference height. Take care, bob must not be in contact with datum plate or sediment build up. • Hold tape and/or bob in the gauging position long enough for the liquid/water to react with paste. • Read and record to nearest 1/8’’ tape mark at reference point.
ALTERNATE INNAGE METHOD CONTINUES.... • Withdraw tape, read and record the bob/tape to nearest 1/8’’ at liquid cut on the bob or at colour change. • Compute as follows: • Gauge = Reference height- tape reading of step 6 + reading from step 7. • For liquid gauging repeat steps 2 through 8 until two gauges agree. • Clean the gauge tape • Record reading on the measurement ticket or other accounting document.
ULLAGE (OUTAGE) METHOD • Verify tape or bob not kinked or worn, if more than 1/16’’ worn, do not use. • Clean tape and bob • Apply a thin coat of oil or water indicator paste • With tape in contact with edge of the gauge hatch, lower tape and bob till partial immersion of bob in liquid. • Hold tape long enough (30 to 60 seconds) • Read and record to the nearest 1/8’’ at the reference point
ULLAGE (OUTAGE) METHOD CONTINUES... • Withdraw the tape and bob, read and record to the nearest 1/8’’ at the point where the liquid cuts the bob or colour change on paste. • Compute by: step 6 + step 7 • For gauging, repeat steps 2 through 8 until the gauges agree. • Clean tape and bob. • Report average gauging on ticket or accounting document.
TANK TEMPERATURE DETERMINATION • Approved equipment- Mercury in glass thermometer of API 2545 or ASTM D1085 • Model: the cup case or flushing case type • Accuracy +/-0.50F • TANK TEMPERATURE MEASUREMENT • Sample can filled to a desired level • At level, gently move up and down for about 2 minutes for equilibrium
TEMPERATURE MEASUREMENT CONTINUATION... • The can withdrawn and held just below the shelter of the gauge hatch and thermometer inserted • At equilibrium temperature is observed and recorded. • Reading on batch – up device is taken for comparison. • After, a “ cocktail” of all sample is formed into a sample container properly labelled indicating:
TEMPERATURE MEASUREMENT... • Date of sampling and date of sampler • Tank number and depth(s) at which sample was taken. • Grade of oil sampled. • Gross quantity of oil represented by sample . • Name of tanker in respect of shipment. • Average tank temperature.
PRINCIPLE FOR SAMPLING VERTICAL TANK • One sample from a tank oil level of 10ft and below and taken from the middle. • Between 10ft – 15ft, two samples: • Upper sample – taken from 1/6thfrom top of oil level. • Lower sample – from the level of the fixed tank outlet. • Above 15ft – three samples: • Upper sample – middle of the upper third portion • Middle sample – middle of tank content • Lower sample – fixed tank outlet or mid-point of the lower third.
SAMPLING • In other that the oil is acceptable, it has to be measured, sampled and tested to standard 2546 API and ASTM D-270-65 • MANUAL SAMPLING • True representation of composite sample of tank content.
SAMPLING(SPECIFICATION FOR APPARATUS) • Thief can must be corrosive resistant metal • Minimum length of 12ft with ID and OD of 13/4” min and 31/2” max. respectively. • Can of bomb or core thief trap with outside graduations of at least 1/8” • Can equipped with a wind shield while taking the temperature of the sample. • Must have cord for sampling at predetermined depths and hook for hanging the can. • Equipped with mechanical shutter for filling and retention of sample at depth of interest.
Manual sample in accordance with ASTM standard no.D4057 of API 2545 • For every shipment, the terminal operator shall obtain four ( two litre) samples for the following uses: • One (two litre) sample for laboratory determination of the crude cargo quality at the terminal. • One (two litre) to be retained at the terminal for 90 days for confirmatory test in case of a dispute.
Manual sample with ASTM standard continues...... III Two (two litre) samples for tank master for consignee test at port of discharge. IV Rubber stopper must not be used for container cover, but cork, glass stoppers or screw cap.
SAMPLER PROBE SPECIFICATION • The sampler shall be in- line- grab type • Capable of continuous sampling during operations • Probe actuation by either pneumatically, hydraulically or electrically via a calibrated flow meter. • Flow proportionally meter with an accuracy of +/- 10% over the working flow range of the pipeline. • Sampling aperture 6mm diameter minimum.
ATOMATIC SAMPLING AT CUSTUDY TRANSFER POINT • It enables automatic sampling representative of sample of the fluid flowing in the pipeline to be obtained. • It is used for obtaining samples of crude oil when fiscal quantity is being determined during dynamic measurement method. • It can also be used during static measurement as authorized by DPR.
SAMPLE RECEIVER • Fixed volume type • Inside made of polished stainless steel to minimize corrosion and water cling age. • Shall be equipped with a relief valve, set at a pressure slightly less than the line pressure • Shall be equipped with a means of monitoring the level of the filling crude in the container. • The bottom shall slope to facilitate withdrawal
Density, S.G or API of Crude Petroleum and liquid Petroleum Product.(IP160/82 ASTMD 1298-80) METHOD • Sample brought to prescribed temperature • Transferred to a cylinder at approximately same temperature. • Prescribed hydrometer is lowered into sample and allowed to settle. • At equilibrium, tem. hydrometer scale is read. • Temperature of sample noted • If necessary a constant-temp bath be used to avoid temperature variation.
Density measurement cont... • The change in mass is used with calibration data. • Thus the determined value is read from the data.
Water and Sediment in Crude oil by the Centrifuge method (IP 359/82 ASTMD 4007-81) • Equal volumes of crude oil and water saturated toluene are placed into a cone shaped centrifuge tube. • The sample is centrifuged • The volume of the higher gravity water and sediment layer at the bottom of the tube is read.
Water in Crude oil by distillation (IP 358/82 ASTMD4006-81) • 100ml of sample is taken • Equivalent volume of reagent (toluene) are poured into the distillation flask. • The dean and stark apparatus made of a condenser and a graduated receiver setup • Sample is boiled under reflux at a controlled temperature • Volume read and expressed as percentage
DENSITY MEASUREMENT CONT... • The density, specific gravity, or API gravity by the hydrometer method is most accurate at 0’’ near reference temperature of 15oC or 60of. • Density and relative density by the digit density method (IP 365/84 ASTMD 4052-81) • An approx. 0.7ml of a liquid sample is introduced into an oscillating sample tube. • The change in the mass of the tube causes a change in oscillating frequency.
AUTOMATIC SAMPLING CONTINUES... • Since custody transfer processes are in batches, sampling by this method is the continuous sampler, flow responsive (proportional) that is a sampler that automatically adjusts the quantity of samples in proportion to the rate of flow.