ISO 3170 Petroleum liquids - Manual sampling
1 Scope
This International Standard specifies the manual methods to be used for obtaining samples of liquid or semi-liquid hydrocarbons, tank residues and deposits from fixed tanks, railcars, road vehicles, ships and barges, drums and cans, or from liquids being pumped in pipelines.This International Standard specifies the manual methods to be used for obtaining samples of liquid or semi-liquid hydrocarbons, tank residues and deposits from fixed tanks, railcars, road vehicles, ships and barges, drums and cans, or from liquids being pumped in pipelines.
It applies to the sampling of petroleum products, crude oils and intermediate products, which are stored in tanks at or near atmospheric pressure, or transferred by pipelines, and are handled as liquids at temperatures from near ambient up to 200 °C.
The sampling procedures specified are not intended for the sampling of special petroleum products which are the subject of other International Standards, such as electrical insulating oils (IEC 60475), liquefied petroleum gases (ISO 4257), liquefied natural gases (ISO 8943) and gaseous natural gases (ISO 10715).
NOTE For the purposes of this International Standard, the term "% (m/m)" is used to represent the mass fraction.
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.
ISO 1998 (all parts), Petroleum industry - Terminology
ISO 2859-1:1999, Sampling procedures for inspection by attributes - Part 1: Sampling plans indexed by acceptable quality limit (AQL) for lot-by-lot inspection
ISO 3171:1988, Petroleum liquids - Automatic pipeline sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1998 and the following apply.
3.1 acceptable quality level (AQL)
maximum per cent defective (or the maximum number of defects per hundred units) that, for purposes of sampling inspection, can be considered satisfactory as a process average
3.2 all-level sample
sample obtained with an apparatus which accumulates the sample while passing in one direction only through the total liquid height, excluding any free water
3.3 automatic sampler
device used to extract a representative sample from the liquid flowing in a pipe
NOTE The automatic sampler generally consists of a probe, a sample extractor, an associated controller, a flow measuring device, and a sample receiver.
3.4 batch
collection of packages containing a product of a single type and composition and of a single manufactured lot, or of a single delivery
3.5 bottom sample
spot sample taken from the product at or close to the bottom of a tank or container
See Figure 1.
3.6 bottom water sample
spot sample of free water taken from beneath the petroleum in a tank
3.7 closed sampling
process of taking samples within a tank under closed conditions, which does not permit the release of any tank contents or vapour to the atmosphere
3.8 composite sample
sample obtained by combining a number of spot samples in defined proportions so as to obtain a sample representative of the bulk of the product
3.9 dipper sample
sample obtained by placing a dipper or other collecting vessel in the path of a free-flowing stream to collect a definite volume from the full cross-section of the stream at regular time intervals for a constant time rate of flow, or at time intervals varied in proportion to the flow rate
NOTE This method is normally restricted to sampling petroleum coke from conveyor belts.
3.10 drain sample
sample obtained from the water draw-off valve on a storage tank
NOTE Occasionally, a drain sample may be the same as a bottom sample, for example, in the case of a tank car.
3.11 floating roof sample
spot sample taken just below the surface to determine the density of the liquid on which the roof is floating
3.12 grease sample
spot sample obtained by scooping or dipping a quantity of soft or semi-liquid material from a container
3.13 integrity of the sample
condition of being complete and unaltered, i.e. the sample being preserved with the same composition as when it was taken from the bulk of the liquid
3.14 lower sample
spot sample taken at a level of five-sixths of the depth of liquid below the top surface
See Figure 1.
3.15 middle sample
spot sample taken at a level of one-half of the depth of liquid below the top surface
See Figure 1.
3.16 mixer
device which provides a homogeneous mixture of the liquid within a pipeline or container in order to obtain a representative sample
3.17 open sampling
process of taking traditional samples within a tank via an open gauge hatch or gauging access point
NOTE If the tank ullage space is pressurized, it will normally be necessary to use other (closed or restricted) procedures to avoid de-pressurizing the tank and the consequent loss of volatile organic compounds (VOCs).
3.18 per cent defective
one hundred times the number of defective units of product contained in any given quantity of units of product divided by the total number of units of product inspected, i.e.:
per cent defective = number of defectives/number of units inspected × 100
3.19 portable sampling device (PSD)
housing designed to provide a gas-tight connection to a vapour-lock valve, which contains a restricted or closed system sampler and is fitted with a tape or cable winding mechanism for lowering and retrieving the sampler
3.20 representative sample
sample having its physical or chemical characteristics identical to the volumetric average characteristics of the total volume being sampled
3.21 residues and deposits
organic and inorganic matter, together with any water dispersed within it, which has separated from the liquid and either fallen to the bottom of the tank containing the liquid, or been left in the tank after the liquid has been pumped out
3.22 restricted sampling
process of taking samples within a tank using equipment which is designed to substantially reduce or minimize the vapour losses that would occur during open sampling, but where the equipment is not completely gas-tight
3.23 running sample
sample obtained with an apparatus which accumulates the sample while passing in both directions through the total liquid height, excluding any free water
3.24 sample conditioning
mixing necessary to homogenize the sample during sample handling in preparation for subsampling and/or analysis
3.25 sample handling
any conditioning, transferring, dividing and transporting of the sample
NOTE Sample handling includes transferring the sample from the primary sampling device to any secondary container, and the transferring of subsamples to the laboratory apparatus in which it is to be analyzed.
3.26 sample size
number of samples to be drawn from a batch to determine its acceptability as given in sampling plans
3.27 skim sample
surface sample
spot sample taken from the surface of the liquid
See Figure 1.
3.28 spot sample
sample taken at a specific location in a tank or from a flowing stream in a pipe at a specific time
3.29 static mixer
mixing device having no moving parts and located within a pipe or tube
NOTE The effectiveness of the static mixer depends on the kinetic energy of the moving liquid for the energy required to mix the liquid.
3.30 still-well
guide pole
still-pipe
sounding-pipe
stand pipe
vertical cylindrical pipe built into a tank to permit gauging operations while reducing errors arising from turbulence or agitation of the liquid
NOTE 1 Samples taken from unperforated or unslotted still-wells should not be used for custody transfer applications, see 7.2.1.3.
NOTE 2 Still-wells may also be found on ships and barges.
3.31 suction-level sample
outlet sample
sample taken at the lowest level from which liquid hydrocarbon is pumped from the tank
See Figure 1.
NOTE In determining this level, appropriate allowance is made for any fittings within the tank such as swing-arm, suction baffle or internal bend.
3.32 sump sample
spot sample taken from within a sump
3.33 suspended water
water within the oil that is finely dispersed as small droplets
NOTE It may, over a period of time, either collect as free water or become dissolved water, depending on the conditions of temperature and pressure prevailing.
3.34 tap sample
tank-side sample
spot sample taken from a sample tap on the side of a tank
3.35 test portion
portion of a sample or subsample that is introduced into the analytical test apparatus
3.36 top sample
spot sample obtained 150 mm below the top surface of the liquid
See Figure 1.
3.37 total water
sum of all the dissolved, suspended and free water in a cargo or parcel of oil
3.38 ullage
empty capacity left in a fixed volume sample receiver/container above the liquid surface
3.39 upper sample
spot sample taken at a level of one-sixth of the depth of liquid below the top surface
See Figure 1.
3.40 vapour-lock valve
vapour control valve
device fitted to the top of vapour-tight or pressure tanks to permit manual measurement and/or sampling operations to be carried out without loss of pressure
3.41 zone sample
core sample
flow-through sample
sample taken as that part of the liquid column which is trapped within the whole height of a sampler when it is sealed at a single spot location within a tank, after having been fully flushed as it was lowered to that position