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Shore
Inspection - After Discharge
- Shore
Lines and Tanks
Determine the nature and
quantities of material in the shore lines prior to taking closing
gauges or meter readings.
Verify that all valves are in
the proper open or closed positions and that any seals which were
installed prior to discharging are still intact by walking along the
pipeline. The nature of the shore line content is determined
by sampling the line contents. Report the findings and
included the line volume in the quantity calculations, if necessary.
If the line fill condition
after discharge differs from the condition prior to discharge, it is
necessary to account for the differences in the respective volumes.
- Tank
Measurements
Take closing gauges,
temperatures, closing tank samples and free water measurements of each
tank used in the discharge operation. Obtain the reference
height from the tank calibration tables before the gauges and water
cuts are taken, Any difference between the observed reference
height and the reference height shown on the tank calibration tables
should be noted and investigated. Ullage and innage
measurements should be taken for the purpose of comparison.
The results will determine which gauges should be used for volume
determination of the investigation.
The
heavy nature of some products may require an outage
measurement. Products with densities heavier than water may
require a water cut on top of the product.
If
time permits, wait for the liquid level to reach equilibrium.
When the inherent nature of a product requires a full 24 hours of
settling time before closing gauges are taken, an insurance or
preliminary gauge or gauges should be taken. Then the inlet
and outlet valves on each tank should be sealed with the valves in the
closed position. If it is impossible to wait, state in the
remarks section of the inspection report the reasons for not
waiting. Compare manual gauges with automatic gauge readings
and record the findings in the inspection report.
All
gauges should be recorded only after securing two identical
measurements that have been read to the nearest 1/8th
inch (0.01 foot / 3 millimetres). On tanks with floating
roofs, gauging should be avoided while the roof is in the critical
zone. The placement of roof legs on high or low position and
the critical zone should be noted in the inspection report.
- Tank Temperatures
The temperature determination
of petroleum cargoes in a shore tank is critical to the custody
transfer process. At the time of gauging, therefore,
temperatures should be carefully taken in accordance with
procedures. Heavy cargoes, heated cargoes and cargoes in
unheated tanks in very cold weather may tend to have temperature
stratification within each tank. When this situation is
suspected, extra temperature measurements should be taken. On
high heat cargoes such as asphalt, it may be impossible to obtain
representative temperatures using cupcase or electronic
thermometers. It may be necessary to use permanently
installed temperature measuring devices. The use of
permanently installed measuring devices should be noted in the report
along with data on when and how the accuracy was verified.
It may be noted that
temperatures taken at or near heating elements may distort the
temperature profiles.
- Tank
Samples
Each shore tank that has
received cargo should be sampled in sufficient quantity to meet
requirements of the interested parties and regulating agencies.
Specify in the inspection
report the tank locations from which the samples were obtained and the
steps that were followed in obtaining a representative sample.
When heavy products are
sampled, the shore tank product height should be divided into three
parts to test for any stratification. The three levels are to
be sampled separately by taking a spot sample inside (approximate
middle) each level.
Sample containers must be clean
and for petroleum products should be flushed with the product prior to
drawing the sample. Sample containers must meet the
requirements of MPMS Chapter 8.1. Containers that are used
for transport and storage of samples must meet appropriate regulatory
requirements. If manual sampling is required, it is strongly
recommended that samples be taken from multiple levels in the tank and
individually tested for stratification.
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Automatic Sampler
If an automatic sampler is
used, make certain that the correct sample volume was
obtained. Witness the mixing of the contents of the sample
receptacle and the withdrawal and testing of the sample.
Report any difficulties that occur with the in-line sampling procedures.
- Meters
Record the closing meter
readings and the meter factor used. Obtain a completed copy
of all meter proving forms and meter measurement tickets.
Attach them to the completed Metered Quantity Report and include them
in the inspection report. If the meter or meters were not
proved during discharge, indicate the frequency of meter proving and
attach a copy of all current meter proving reports. The
discharge port form should be similar to the standard meter proving
form in MPMS Chapter 12.2
If manual and/of automatic
shore tank measurements were taken, show a comparison with metered
volumes.
Sections of text taken from API - MPMS Chapter 17 Marine Measurement
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