原文: 石油及液体石油产品立式金属罐交接计量规程 （SY/T 5669—93）

石油及液体石油产品立式金属罐交接计量规程 （SY/T 5669—93）

本规程适用于采用常压立式金属罐，对贮存的石油及液体石油产品（以下简称油品）在静止状态下所进行的交接计量。 执行本规程时，必须履行石油工业部颁发的《石油及液体石油产品交接计量管理办法》的有关管理规定。 1总则 1.1计量精度 按本规程进行油品交接计量的误差为±0.35%。 1.2容器检定 1.2.1立式金属罐容积的检定，按JJG 168《立式金属罐容积检定规程》执行。 1.2.2立式金属罐容积的检定周期：初检为三年，复检为五年。 1.2.3用于油品计量的立式金属罐，由石油工业部批准的各大容器检定站进行检定。 2计量器具与试剂 2.1量尺 2.1.1量油尺应采用钢卷尺，尺的长度根据罐的大小可选择10米、15米、20米三种规格之一，最小刻度1毫米。并附有出厂合格证和校正表。 2.1.2量油尺的尺锤应为铜质材料。计量轻质油品所用500克尺锤；计量原油及重质油品使用1000克尺锤。 2.1.3量水尺应采用铜尺或铝合金尺，尺的长度为300毫米，最小刻度为1毫米，全长误差在±05毫米以内。 2.1.4量尺每半年检定一次。其技术条件应符合JJG 4—80《钢卷尺检定规程》的规定。 2.1.5量尺属于下列情况之一者，禁止使用： a尺带扭折、弯曲及锒接； b尺带刻度模糊不清或数字脱落； c尺锤尖部损坏； d尺的刻度误差超过允许范围； e没有校正表。 2.2温度计 2.2.1测量油品温度用的温度计，一般选用棒状全浸式水银温度计，最小分度值为0.2℃，并附有出厂合格证和校正表。 2.2.2水银温度计每半年检定一次。其技术条件应符合GB/T 514 《石油产品试验用液体温度计技术条件》的规定。 2.2.3水银温度计属于下列情况之一者，禁止使用： a毛细管内的水银柱有断裂现象； b感温泡有裂痕； c刻度不清，涂料脱落； d刻度误差超过允许范围； e没有校正表。 2.2.4使用其他类型的温度计，必须以满足以下条件： a通过国家正式鉴定，列为定型产品； b具有相应的检定规程或技术条件，能实行周期检定； c测量精度应能达到最小分度值为0.2℃水银温度计的同级精度； d采用热一电转换式温度计（如半导体温度计等），必须为防爆产品，并且有防爆级别标志和防爆合格证，传感器与显示仪表之间的接线，应符合防爆、屏蔽等要求。 2.3密度计 2.3.1测定油品密度所用的密度计，应选用SY—1型石油密度计。 2.3.2石油密度计的测量范围，应符合GB/T 1884 《石油和液体石油产品密度测定法（密度计法）》的规定。 2.3.3石油密度计的每半年检定一次。其技术条件应符合SY/T 3301 《石油密度计技术条件》的规定。 2.4测温盒 2.4.1测温盒应由铜质或铝合金材料制成。 2.4.2测温盒的容量不得小于200毫升。 2.4.3测温盒的提拉绳应选用符合防静电要求的材料制作。 2.5取样器 2.5.1取样器就布铜质或铝合金材料制成。 2.5.2取样器的自重应是排出液体重量的1.5~2倍。 2.5.3取样器的容量应符合《石油和液体石油产品取样法》的规定。 2.5.4取样器提拉绳的要求与测温盒提拉绳的要求相同。 2.6试油膏 试油膏应符合以下要求： 均匀地涂在尺上的试油膏浸入15~20℃的120#溶剂汽油中，其颜色发生变化的时间不应超过10秒钟，停留10秒钟与停留20秒钟的示值变化不应超过0.5毫米。 2.7试水膏 试水膏应符合以下要求： 均匀地涂在水尺上的试水膏浸入15~20℃水中，其颜色发生变化的时间不应超过5秒钟，停留5秒钟的示值变化不应超过0.5毫米。 3计量操作方法 3.1操作顺序 油品交接前：先检前尺，后测温、取样。 油品交接后：检后尺并测温。 3.2检尺 3.2.1术语 a检尺点：从油罐罐顶指定下尺的部位。 b检尺总高：从检尺点至罐底（或检尺台）的垂直距离。 c检前尺：测量油品交接前油罐内的液面至罐底（或检尺台）的垂直距离。 d检后尺：测量油品交接后油罐内的液面至罐底（或检尺台）的垂直距离。 e检实尺：测量罐内液面至罐底（或检尺台）的垂直距离。 f检空尺：测量检尺点至罐内液面的垂直距离。 g油痕：被测油品在量油尺带上留下的分界痕迹。 h水痕：被测底水在量水尺面上留下的分界痕迹。 3.2.2液面稳定时间 检尺前罐内液面的稳定时间不少于30分钟。 3.2.3检尺部位 检尺时应在罐顶检尺点下尺。 3.2.4检实尺。 3.2.4.1对计量轻质油品和润滑油类，应检实尺。 3.2.4.2检尺时应做到：下尺稳，触底轻，读数准；先读小数，后读大数；做好记录。 3.2.4.3重复3.2.4.2项操作进行第二次检尺，两次检尺数相差不超过1毫米时，以第一次检尺数为准；超过1毫米，应重新检尺。 3.2.4.4测量易挥发的轻质油品液面，若油痕不清，可涂试油膏检尺。 3.2.5检空尺 3.2.5.1对计量原油及重油、燃料油等重质油品，应检空尺。 3.2.5.2当尺带浸入油内时，停止下尺，使卷尺的刻度与检尺点对准，稳定后读下尺高度，提尺再读被油浸没部分的高度，做好记录。 3.2.5.3重复3.2.5.2项操作进行第二次检尺，两次检尺数相差不超过1毫米时，以第一次检尺数为准；超过1毫米，应重新检尺。 3.2.5.4检空尺时，油面高度等于检尺总高度减去空尺高度再加上浸没高度。 3.2.6检水尺 3.2.6.1测量罐内底水高度的检尺操作方法同检实尺。 3.2.6.2水尺在罐内停留时间为10~30秒钟。 3.2.6.3测量底水高度时，应在水尺上涂试水膏。 3.3测温 3.3..1油罐测温 对测量液体石油产品温度，宜采用在油罐内测温的方法。 3.3.1.1测温前，选择适当量程的温度计安放在测温盒内中部，并将测温盒从检尺点下到测温部位。 3.3.1.2对于在油罐内不需加温的油品，应罐内油品液面高度的1/2处，测温1次。 3.3.1.3对于在油罐内需要加温的油品，应按下列规定进行测温，然后取各次所测温度的算术平均值作为油品的平均温度。 a当罐内油品液面高度超过检尺的总高的1/2时，在罐内液面高度的1/6、1/2、5/6处，分别测温1次； b当罐内油品液面高度低于检尺总高的1/2时，在罐内液面高度的1/3、2/3处，各测温1次。 3.3.1.4测温停留时间如下： 轻质油品不少于5分钟； 润滑油不少于7分钟； 原油、重油、燃料油、高温润滑油等不少于10分钟。 3.3.1.5当测温盒在罐内达到规定时间后，迅速提出，立即读数（此时不要把测温盒内的油倒掉）；读数时，视线应与温度示值呈水平，先读小数，后读大数；做好记录。 3.3.2管线测温 对测量原油温度，宜采用在输油管中测温的方法。 3.3.2.1测温部位应靠近泵出口处。 3.3.2.2按下列规定进行测温，然后取各次所测温度的算术平均值作为油品的平均温度。 a总的输油时间不超过2小时，应在输油开始时罐内油品流过测温点后10分钟、中间时间和输油结束前10分钟，各测温1次； b总的输油时间在2~24小时，应在输油开始时罐内油品流过测温点后10分钟，测温1次，以后每隔1小时，测温1次； c总的输油时间超过24小时，应在输油开始时罐内油品流过测温点后10分钟，测温1次，以后每隔2小时，测温1次。 3.4取样 3.4.1油罐取样 对液体石油产品的试样，宜在油罐内采取。取样方法按SY/T 2001《石油产品取样法》执行。 3.4.1.1取样前，应将样器用被取的油品冲洗一镒。 3.4.1.2把取样器降到罐内取样部位，拉开取样器，将油样倒入备有标签的干净瓶内。 3.4.2管线取样 对采取原油试样，宜采用在输油管中取样的方法。 3.4.2.1取样部位应靠近泵出口处。 3.4.2.2取样管的安装要求如下： a应水平安装在垂直管线上或呈水平呈90°安装在水平管线的流体湍流区（雷诺数Re＞2000）； b取样管入口端的45°斜面应朝向流体流动方向，入口端斜面的中点应位于管径的1/3处； c取样管露出部分应尽量短。 3.4.2.3按下列规定从管线取样器中采取时间比例样，然后将各次所采取的试样以相等的体积掺合成一份间歇样。 a总的输油时间不超过2小时，应在输油开始时罐内油品流过10分钟、中间时间和输油结束前10分钟，各取样1次； b总的输油时间在2~24小时，应在输油开始时罐内油品流过取样点后10分钟，取样1次，以后每隔1小时，取样1次。 c总的输油时间超过24小时，可在输油开始时罐内油品流过取样点后10分钟，取样1次，以后每隔2小时，取样1次。 3.4.2.4取样前，应放出一些要取样的油品，将取样器冲洗干净，然后把试样收集在试样容器或收集器中。 3.4.2.5采取高凝点试样时，要注意取样管段的保温，防止油品凝固。采取挥发性试样时，要防止轻馏分损失。 3.5密度测定 油品密度的测定方法，按GB/T 1884《石油和液体石油产品密度测定法（密度计法）》执行。对所采取的试样，均进行密度和温度的测定，每个试样连续测定2次，密度计读数估至0.0001克/厘米3，温度读准至0.2℃。 3.6原油含水测定 原油含水率的测定方法，按GB/T 260—77《石油产品水分测定法》执行。对所采取的试样应作水分含量的平行测定，取平行测定的两个结果算术平均作为被测原油的含水量。数据以重量百分数表示。 4油量计算 4.1密度的换算 查GB/T 1885标准中表1《石油视密度换算表》将密度计在t℃下测得的油品视密度（ρ′t）换算为标准密度（ρ′20）。 4.2标准体积的计算 4.2.1根据检尺测得的油高查油罐容积表，得到表载体积V表。 4.2.2根据检尺测得的水高查油罐容积表，得到罐底明水体积V表水。 4.2.3计算静压力容积增大值△Vp： △Vp=△Vp水•D204 式中：△Vp——罐内油品的静压力容积增大值； △Vp水——水的静压力容积增大值； D204——罐内油品标准密度和4℃纯水密度的比值（为ρ20值）。 4.2.4对油品温度与标准温度相差不超过±10℃时，油品体积（Vt）计算如下： Vt=V表+△Vp-V表水 4.2.5对油品温度与标准温度相差超过±10℃时，油品体积（Vt）按下式计算： Vt=(V表+△Vp-V表水）•［1+0.0000036(t-20)］ 式中：0.0000036——钢罐的体膨胀系数（1/℃）； t——罐体钢板温度，其值可采用油温。 4.2.6计算在20℃温度下，油品的标准体积（V20） V20=K•Vt 式中：K——石油体积系数。其值查GB/T 1885表ⅡA《石油体积系数表》得出。 4.2.7标准体积V20也可用下式计算： V20=Vt［1-f（t-20）］ 式中：f——石油体积温度系数（1/℃），其值查GB/T 1885表ⅡB《石油体积温度系数表》得出。 4.2.8为减少用K值和f值两种计算公式因取值不同所产生的差值，在计算时，所用K值和f值均应算到小数第五位。对这两种计算结果，如有争议，以用K值计算的结果为准。 4.3质量的计算 油品以空气中的重量计量时，应考虑空气浮力的影响。将真空中的质量（M）换算到空气中的重量（m）。 4.3.1以空气浮力修正值进行修正的计算公式为： m=(ρ20-0.0011)•V20(1) 式中：0.0011——油品密度的空气浮力修正值（克/厘米3）。 4.3.2以空气浮力修正系数进行修正的计算公式为： m=ρ20•V20•F(2) 式中：F——空气浮力修正系数，其值根据油品的标准密度查GB/T 1885表ⅢB《石油真空中质量换算到空气中重量换算系数表》得出。 4.3.3如对4.3.1中（1）式与4.3.2中（2）式的计算结果有争议时，以4.3.2中（2）式计算的结果为准。 4.4原油纯油量的计量 对于原油的交接计量，在计算油量时，应扣除原油中的含水量。原油纯油量的计算公式如下： m-c=m•(1-W) 式中：m-c——原油纯油重量； m——混合原油重量； W——原油试样的水分重量百分含量。 5注意事项 5.1上罐检尺前，应榆计量器具、试剂是否完好，并准备好记录。 5.2计量员在计量前，应了解将要计量的油罐贮油情况。 5.3在测量挥发性较强的轻质油品液面时，不准在量油尺带上涂抹粉笔等其他物质。 5.4在测量罐内底水高度时，不允许使用试水纸。 5.5上罐操作时计量员应站在上风头。 5.6计量员上罐操作，必须采取消除静电的措施。 5.7照明应采用防爆灯具。 5.8油罐检尺部位应衬不产生火花的金属。 5.9不得穿带钉鞋和人造纤维制作的服装上罐操作。 附加说明： 本规程由石油工业部运销司提出并归口。 本规程由石油工业部《石油及液体石油产品交接计量规程》编写组负责编制。

译文: Petroleum and liquid petroleum products -- Vertical metal tank custody transfer measurement specification

 

Standard of the Ministry of Petroleum Industry of the People’s Republic of China

Petroleum and liquid petroleum products -- Vertical metal tank custody transfer measurement specification

This specification covers the custody transfer measurement of petroleum and liquid petroleum products (PP) under normal pressure in stationary using vertical metal tank gauges.

This specification should be carried out in accordance with related regulations of the Petroleum and liquid petroleum products -- Administration for custody transfer measurement issued by the Ministry of Petroleum Industry of the People’s Republic of China.

1.    General

 

1.1 Measurement Accuracy

Custody transfer measurement error in this specification is +/- 0.35%.

1.2 Container Verification

1.2.1      Capacity of vertical metal tanks is verified in accordance with JJG 168-76 Capacity verification specification of vertical metal tanks.

1.2.2      Period for capacity verification of vertical metal tanks: initial check within three years and recheck within five years.

1.2.3      Vertical metal tanks used for PP measurement are verified by container verification stations approved by the Ministry of Petroleum Industry of the People’s Republic of China.

2.    Measurement Tools and Agents

 

2.1 Gauging Tape

2.1.1      Certified and calibrated tapes used for petroleum measurement are steel tapes with three sizes of length 10m, 15m, 20m (Min Scale: 1mm) which are determined based on the size of tanks.

2.1.2      Plumbs of oil gauging tapes should be made of copper materials. 500g plumbs are used for gauging light petroleum products and 1000g for crude oil and heavy petroleum products.

2.1.3      Water gauging tapes should be made of coppers or aluminum alloy, 300mm long (Min Scale: 1mm) with an error of the full length about +/- 0.5mm.

2.1.4      Gauging tapes are biannually verified in technical accordance with the specifications of JJG 4-80 Verification specification of steel tapes.

2.1.5      Gauging tapes in any of the following conditions should not be used:

a.    with folded, bent and chained tape band;

b.    with blurred scale or number;

c.    with damaged plumb tip;

d.    with exceeded allowable scale error;

e.    without calibration table.

2.2 Thermometer

                       2.2.1   Thermometers used for gauging the temperature of petroleum products are generally mechanical total immersion mercury thermometers (min division 0.2℃) with certificate and calibration table.

                       2.2.2   Mercury thermometers are biannually verified in technical accordance with the specifications of GB 514-65 Technical specification for liquid thermometer for testing petroleum products.

                       2.2.3   Thermometers in any of the following conditions should not be used:

a.       with broken mercury column in capillary tube;

b.       with broken bulb;

c.       with blurred scale and number;

d.       with exceeded allowable scale error;

e.       without calibration table.

                       2.2.4   Thermometers of other types should be:

a.    verified and listed in national approved products;

b.    periodically verified according to relevant verification specifications or technical specifications;

c.    with the same measurement accuracy as mercury thermometer’s (minimum scale 0.2℃);

d.    thermo-electrical thermometer (e.g. semiconductor thermometer etc.) which is explosion-proof product provided with explosion proof grade and certificate and explosion-proof and shielded connections between sensor and displayer.

2.3 Hydrometer

                       2.3.1   Hydrometer used for the density determination of petroleum products is SY-1 petroleum hydrometer.

                       2.3.2   Measurement range of petroleum hydrometer should be in conformity with GB/T 1884 Petroleum and liquid petroleum products - Density determination (Hydrometer method).

                       2.3.3   Petroleum hydrometer should be verified once every half year and its technical specification should be in conformity with SY/T 3301 Technical specification of petroleum hydrometer.

2.4 Test Kit

                           2.4.1   Test kit should be made of copper materials or aluminum alloy materials.

                           2.4.2   Capacity of test kit should be not less than 200 ml.

                           2.4.3   Lifting rope of test kit should be made of antistatic materials.

2.5 Sampler

                           2.5.1   Sampler should be made of copper materials or aluminum alloy materials.

                           2.5.2   Weight of sampler should be 1.5~2 times of the weight of discharged liquid.

                           2.5.3   Capacity of sampler should be in conformity with the Petroleum and liquid petroleum products - Sampling method.

                           2.5.4   Lifting rope of sampler should be made of antistatic materials.

2.6 Oil Indicating Paste

Requirements for oil indicating paste:

No longer than 10 seconds of color change when immerging the oil indicating paste evenly coated on gauge into 120# solvent gasoline under 15~20℃ and no more than 0.5 mm difference between indicating values after 10 seconds and 20 seconds.

2.7 Water Indicating Paste

Requirements for water indicating paste:

No longer than 5 seconds of color change when immerging the water indicating paste evenly coated on water gauge into 120# solvent gasoline under 15~20℃ and no more than 0.5 mm difference between indicating values during 5 seconds.

3.    Measurement Methods

                     3.1     Sequence of Operation

Before transfer: first check the HBT, then measure temperature and take sample.

After transfer: check the HAT and measure temperature.

                     3.2     Gauge

                                   3.2.1   Glossary

a.    Gauge point: position specified for run gauge from the top of tank.

b.    Total gauging height: vertical height from gauge point to bottom tank (or gauge platform).

c.    HBT: the vertical height from liquid level in tank to bottom tank (or gauge platform) before transfer.

d.    HAT: the vertical height from liquid level in tank to bottom tank (or gauge platform) after transfer.

e.    Content height: the vertical height from liquid level in tank to bottom tank (or gauge platform).

f.     Ullage height: the vertical height from gauge point to liquid level in tank.

g.    Oil mark: boundary mark on oil gauge by measured oil.

h.    Water mark: boundary mark on water gauge by bottom water.

                                   3.2.2   Stable duration of liquid level

Liquid level in tank before gauging is kept stable not shorter than 30min.

                                   3.2.3   Gauging position

Gauge is run from the gauging point at the top of tank.

                                   3.2.4   Content height gauge

                                                 3.2.4.1Gauge content height when measuring light petroleum products and lubricant oil.

                                                 3.2.4.2Gauging requirements: stably run gauge, lightly contact bottom, clearly read; read small scale, then large scale and record.

                                                 3.2.4.3Repeat 3.2.4.2; the 1^st read prevails when equal to or less than 1mm difference exists between two gauges; repeat gauging when more than 1mm difference.  

                                                 3.2.4.4Oil indicating paste can be used for unclear oil mark when measuring liquid level of volatile light oil.

                                   3.2.5   Ullage height gauge

                                                 3.2.5.1Gauge ullage height when measuring crude oil, heavy oil and fuel oil etc.

                                                 3.2.5.2Stop running gauge when tape is immerged in oil and align tape scale with the gauge point; read and record the height when stable and read the immersion height after lifting the gauge.

                                                 3.2.5.3Repeat 3.2.5.2; the 1^st read prevails when equal to or less than 1mm difference exists between two gauges; repeat gauging when more than 1mm difference.

                                                 3.2.5.4For ullage height gauge, oil level height = total gauging height -- ullage height + immersion height.

                                   3.2.6   Water gauge

                                                 3.2.6.1Gauge the height of bottom water in tank as gauging the content height.

                                                 3.2.6.2Keep the water gauge in tank for 10~30min.

                                                 3.2.6.3Coat water indicating paste on water gauge when gauging the water height.

                     3.3     Temperature Determination

                                   3.3.1   Oil tank temperature determination

Temperature of liquid petroleum products should be measured inside the tank.

                                                 3.3.1.1Before temperature determination, put a thermometer of appropriate scale into the middle of the temperature determination kit and lay down the kit to the temperature measuring point from gauge point.

                                                 3.3.1.2Take one measurement at the middle height of oil for oil which needs not to be heated in tank.

                                                 3.3.1.3Average temperature of oil which needs to be heated in tank is measured step by step and calculated based on each measurement as follows:

a.    Take measurements respectively at the 1/6, 1/2 and 5/6 points of the height of liquid level when height of liquid level is higher than 1/2 of total gauging height.

b.    Take measurements respectively at the 1/3 and 2/3 points of the height of liquid level when height of liquid level is lower than 1/2 of total gauging height. 

                                                 3.3.1.4Measurement duration:

Light oil: no less than 5 min;

Lubricant oil: no less than 7 min;

Crude oil, heavy oil, fuel oil and high-temperature lubricant oil etc.: no less than 10 min.

                                                 3.3.1.5Pick up the kit after the specified time limit in tank and read the scale (keep the oil in kit); when reading, keep the view line horizontally aligned with the indicating scale; read and record the smaller scale, then larger scale.

                                   3.3.2   Temperature determination of pipes

Temperature of crude oil should be measured in oil conveying pipes.

                                                 3.3.2.1Measuring point should be near to the pump outlet.

                                                 3.3.2.2Measure as follows and take the average of each measurement as the average temperature of oil.

a.    Total oil-conveying time: no longer than 2 hours. Take measurements respectively 10 minutes after the oil flows through the measuring point after conveying, at the intermediate time and 10 minutes before the end of conveying;

b.    Total oil-conveying time: 2~24 hours. Take a measurement 10 minutes after the oil flows through the measuring point after conveying, then a measurement every one hour;

c.     Total oil-conveying time: more than 24 hours. Take a measurement 10 minutes after the oil flows through the measuring point after conveying, then a measurement every two hours.

                     3.4     Sampling

                                   3.4.1   Oil tank sampling

Sample of liquid petroleum products should be taken in oil tank according to the SY 2001-77 Petroleum products -- Sampling method.

                                                 3.4.1.1Wash the sampler with to-be-sampled oil before sampling.

                                                 3.4.1.2Lay down the sampler into the tank to the sampling point; when the sampler is filled with oil, take it out and pour the oil sample into labeled clean bottle.

                                   3.4.2   Pipe sampling

Sample of crude oil should be taken in oil conveying pipe.

                                                 3.4.2.1Sampling point should be near to the pump outlet.

                                                 3.4.2.2Sampling pipe is installed as follows:

a.    Horizontally installed on vertical pipes or installed in flowing area of horizontal pipes with a 90 degree angle (Re>2000)

b.    45 degree slant at the input end of sampling pipe should be in the same direction as the flowing direction and the slant center of input end should be at the 1/3 point of caliper;

c.    Exposed part of sampling pipe should be very short.

                                                 3.4.2.3Take time scale samples from pipe sampler as follows and mix each sample with the equal volume to be an intermittent sample.

a.    Total oil-conveying time: no longer than 2 hours. Take samples respectively 10 minutes after the oil flows through the measuring point after conveying, at the intermediate time and 10 minutes before the end of conveying;

b.    Total oil-conveying time: 2~24 hours. Take a sample 10 minutes after the oil flows through the measuring point after conveying, then a sample every one hour;

c.     Total oil-conveying time: more than 24 hours. Take a sample10 minutes after the oil flows through the measuring point after conveying, then a sample every two hours.

                                                 3.4.2.4 Take some to-be-sampled oil to clean the sampler before sampling, and then collect the sample in sample container or collector.

                                                 3.4.2.5Keep the temperature of sampling pipe when taking high freezing point samples to avoid solidification.

                     3.5     Density Determination

Density of petroleum products is determined according to the GB 1884-80 Petroleum and petroleum products -- Density determination method (Hydrometer method). Density and temperature of each taken sample should be measured twice and reading of hydrometer should be correct to 0.0001 g/cm3, temperature to 0.2℃.

                     3.6     Determination of Water Cut in Crude Oil

Water cut in crude oil is determined according to the GB 260-77 Petroleum products -- Determination method of water cut. Water cut of crude oil in percentage is the average value of two results of parallel determination of water cut which is made necessary for samples.

 

4.    Petroleum Volume Calculation

                     4.1     Calculation of Density

In table I of GB 1885-80 standard -- Petroleum apparent density conversion table, apparent density (ρ’_t) of petroleum products measured by hydrometer under t ℃ is converted to be standard density (ρ₂₀).

                     4.2     Calculation of Standard Volume

                                   4.2.1   If given the gauged oil height, content volume V_c will be got according to the oil tank volume table.

                                   4.2.2   If given the gauged water height, volume of bottom water V_w will be got according to the oil tank volume table.

                                   4.2.3    Volume increment △V_p under the static pressure is:

△V_p = △ V_water * D²⁰₄

Wherein:

△V_p  -- volume increment of petroleum products in tank under static pressure;

△ V_water -- volume increment of water under static pressure;

D²⁰₄ -- ratio of petroleum standard density and pure water density under 4 ℃ (ρ₂₀) .

                                   4.2.4   If the difference between petroleum temperature and standard temperature is no more than +/- 10℃, petroleum volume (V_t) should be:

V_t = V_c + △V_p - V_c-water

                                   4.2.5   If the difference between petroleum temperature and standard temperature is more than +/- 10℃, petroleum volume (V_t) should be:

V_t = (V_c + △V_p - V_c-water) * [1 + 0.000036(t - 20)]

Wherein:

0.000036 -- volumetric expansion coefficient of tank (1/℃)

t -- temperature of steel plate of tank, which can be oil temperature.

                                   4.2.6   Standard volume (V₂₀) of petroleum products under 20℃:

V₂₀ = K * V_t

Wherein:

K -- petroleum volume coefficient in GB 1885-80 standard Table II A -- Petroleum volume coefficient table.

                                   4.2.7   Standard volume (V₂₀) is:

V₂₀= V_t [1 -- f (t - 20)]

Wherein:

f -- petroleum volume-temperature coefficient (1/℃) in CB 1885-80 Table II B Petroleum volume-temperature coefficient table.

                                   4.2.8   K and f should be round up after the fifth decimal point when calculating to reduce value difference.  Result calculated with K prevails if differences exist between the results calculated in above two methods.

                     4.3     Calculation of Mass

Effect of air buoyancy should be considered when gauging the petroleum with weight in air, and then the mass (M) in vacuum is conversed to weight (m) in air.

                                   4.3.1   If given the correct value of air buoyancy, the computing formula should be:

m = ( ρ₂₀ -- 0.0011) * V₂₀                              (1)

wherein: 0.0011 -- correct value of air buoyancy of petroleum density (g/cm³).

                                   4.3.2   If given the correct coefficient of air buoyancy, the computing formula should be:

m = ρ₂₀  * V₂₀ *F                                     (2)

wherein: F -- correct coefficient of air buoyancy obtained from GB 1885 -80 Table III B Coefficient table for conversing petroleum mass in vacuum to weight in air according to the standard petroleum density.

                                   4.3.3   Calculation result of formula (2) in 4.3.2 prevails when controversy exists between the calculation result of formula (1) in 4.3.1 and formula (2) in 4.3.2.

                     4.4     Pure Oil Measurement of Crude Oil

Water content should not be included in crude oil when calculating the oil mass in crude oil transfer measurement. Pure oil in crude oil is calculated as follows:

m_c^- = m * (1 -- W )

wherein: m_c^- -- weight of pure oil in crude oil;

m -- weight of mixed crude oil;

W-- water weight percentage in crude oil sample.

5.    Notes

                     5.1     Check that measurement instruments and agents are in good conditions and record while checking.

                     5.2     Get to well know the tank oil to be gauged before gauging.

                     5.3     Do not smear chalks on tape of oil gauge when measuring liquid level of strongly volatile light petroleum products.

                     5.4     Don not use water indicating paper when measuring the height of bottom water in tank.

                     5.5     Gauge at the uptake of tank.

                     5.6     Eliminate static when gauging.

                     5.7     Use explosion-proof lights for illumination.

                     5.8     Line spark-free metal at the gauging point of tank.

                     5.9     Do not wear spiked shoes and clothes made of artificial fibers when gauging on tank.

Additional Information:

This specification is proposed and managed by the Transportation & Sales Division of the Ministry of Petroleum Industry of the People’s Republic of China.

This specification is compiled by the compiling team of Petroleum and liquid petroleum products -- Transfer measurement specification.

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