Metering Services Provided by AmSpec

AMSPEC can provide you with an onsite Metering Expert to manage and maintain your metering system, over a longer term or just for a short-term basis.  This is especially useful during commissioning and start-up phases of new metering systems.

The Site Metering Expert can also organise onsite training and support for all Client personnel, who will be working closely with or even responsible for operating the Metering System on a daily basis.

The Supplied Metering Expert can also act as the Third Party, to enable the unbiased Independent Calibrations and Measurement Reporting and continued verifications and meter proving etc at the Metering System, on behalf of both Buyer and the Seller or any involved parties or Governmental bodies.

AMSPEC can also provide a 24/7 Expert Metering Engineer support call service.

If the issues cannot be resolved remotely then we can also provide Metering Expert to the client site on Ad-hoc as and when required basis, to support the Metering Systems and Site Personnel.

AMSPEC can provide Classroom and Job Site for all personnel involved with Metering

Training ranges from Familiarity and beginner level, to More Complex Expert Level Training.

Let us know your requirements and we can compile a training course, to suit your own specific company or personnel’s particular needs.

We Provide a full Meter Prover Calibration Service.  Meter Provers are usually calibrated once per year, but this can sometimes be extended on a case by case basis.

Any error in the Meter Prover calibrated volume will have a direct proportional error on the Measured volume, by producing an incorrect Meter factor or K-factor during proving operations and thus introduce errors into the volumetric flow and totals produced through the system.

For example, the Pipe Prover type Meter Prover, is more commonly calibrated, by either Water draw method, or by Use of a Mobile High accuracy Compact Prover and Master Meter, which is transported on site by a specialist third party calibration company.

The Mobile Compact Prover will have been calibrated onshore in a stable environment, using the Gravimetric method or by single Volume Primary Measure using the water-draw method.

Prior to recertification taking place, all of the Prover and Metering critical valves should be checked for seal integrity and operation.  With a Pipe Prover, the 4-way valve in particular, should have good integrity in both flow directions.  It is often good practice to replace the 4-way valve slips and seals prior to an annual calibration. The vent and drain valves on the prover should also have good integrity.

For example, the proving procedure sequence for a Volumetric Pipe Prover is normally as follows:

• Master Compact Prover arrive on site and will be checked and tested for any Volumetric Change (damage in transit) using the water draw technique involving a Primary Measure or Seraphin type delivery vessel.
• Pipe Prover inflatable sphere is removed and checked for damage
• Sphere is checked for optimum inflation size concentricity and inflated or deflated as necessary
• Sphere replaced if not concentric and showing signs of damage that may affect sealing capability.
• Pipe Prover Detector switches are checked for operation and insertion depth and are connected to compact prover control cabin.
• Proving takes place using the operational Petroleum product or in some cases water from either a fire hydrant or suitable pumped water supply (use of water may be due to poor product process stability).
• Any shift in volume greater than 0.02% or run repeatability greater than 0.02% is investigated further and must then verified with a prove at a reduced flowrate (At least 25%). This will indicate any leaks in the system.
• The compact prover is disconnected, and the prover detector switches sealed with lead security seals.
• The prover calibration results are verified, the calibration certificate issued, then the new prover volume downloaded to the prover flow computer.

AMSPEC provides a Flow Meter Calibration Service at the Clients facility or Site location, using a number of various methods.  One of which, is our Mobile Compact Prover unit, used as the Master Volume Prover to prove the meter at site.

But in some circumstances, it can sometimes be complex and the Size of the Flow Meter or the flow rates or process conditions, may require that the flow meter has to be removed and sent to an accredited laboratory for a traceable calibration.

This is quite common for Master Meters, where no higher traceable standard is available at the client’s facility.

There is usually a requirement to calibrate the meter over its expected range and process conditions.

It is often useful or required to appoint an experienced Third-party Flow Meter Calibration witness to ensure that the calibration runs smoothly. AMSPEC can also provide this Third-party Witnessing Service.

AMSPEC provides a Flow Meter Calibration Service at the Clients facility or Site location, using a number of various methods.  One of which, is our Mobile Compact Prover unit, used as the Master Volume Prover to prove the meter at site.

But in some circumstances, it can sometimes be complex and the Size of the Flow Meter or the flow rates or process conditions, may require that the flow meter has to be removed and sent to an accredited laboratory for a traceable calibration.

This is quite common for Master Meters, where no higher traceable standard is available at the client’s facility.

There is usually a requirement to calibrate the meter over its expected range and process conditions.

It is often useful or required to appoint an experienced Third-party Flow Meter Calibration witness to ensure that the calibration runs smoothly. AMSPEC can also provide this Third-party Witnessing Service.

Operational / Calibration Procedures

Operational / Calibration Procedures are a guide for the Metering Technician / Engineer on Site to perform Metering calibrations on the Equipment in use.

It is important to document all procedures and processes within a metering system to enable the system to be correctly controlled.  All Operational / Calibration Procedures should be specific for the equipment installed and how it is operated. They should also be specific to the commercial metering maintenance package that is used on the system.

Metering Calibration procedures should be as detailed as possible and include the tolerances, the test equipment to be used and a step by step guide on how to perform the calibration and the steps to take if the test fails.

All metering maintenance activity should be documented, typical tests that are routinely performed are Flow Computer ADC / DAC Verification Tests and Calibrations, Configuration Checks, Calculation checks, such as API MPMS for Correction of Temperature and Pressure and Density compressibility, AGA 8, ISO 6976, ISO 5167, API 11.1 Density Referral etc.

Field Tests include Differential Pressure / Pressure Transmitter footprint check, Pressure and Temperature Transmitter Calibrations, Temperature element Spot check, RTD Input Check, Densitometer Input check, Densitometer Zero and Air checks, Flow rate checks, Totalisation checks etc just as an example but there are many more and in-depth Tests Checks and Calibrations that are carried out.

Functional Design Specification (FDS) / Basis of Design (BOD) Documentation

A Functional Design Specification (FDS), or Basis of Design Document (BOD), forms the terms of reference for any new metering system. The document should describe the system requirements, the standards and guidelines that should be adhered to.

Flow Metering Standards should all be referenced along with the source of all the calculations used. The Functional Design Specification (FDS) or the Basis of Design (BOD) Document, should also outline, the full Range of process conditions with which the Metering System will be used, field or facility production rates and normal operational process conditions, with all calculations and Engineering data covering all scenarios within the scope of use.  Also included will be all the Individual Component data for each instrument or item of Equipment that contributes to the make-up of the overall system.

The Functional Design Specification (FDS) or the Basis of Design (BOD) should always include as much data and specification information as is entirely possible, so that the Metering System is very accurately described, prior to Engineering Construction and beyond.

Fiscal Audit

AMSPEC Provide A full Fiscal Metering Audit service.

A Fiscal Audit will check for Compliance of all the individual components of the Metering System, the criteria are normally provided by the Client or Governing body, but can also be an Audit referencing compliance with International Standards also encompassing procedural use, but will typically cover the following areas:

• Flow Meter (Turbine, PD, Coriolis, Ultra Sonic) Installation, Performance, Calibration, Proving history, Meter repeatability & bad meter pulses log.
• Meter Prover (Volumetric Loop, Tank Prover or Small Volume Prover) certification, detector switches, in use Prover Constants entered in to Flow Computer.
• Orifice plate inspections, meter tube inspections & orifice carrier, installation and certification.
• USM installation, path operation, calculations, certification.
• Coriolis meter installation, Coriolis controller configuration, calibration & certification.
• Densitometer performance, Installation, Tracking, Calibration and Densitometer constants entered in to the Flow Computer.
• Pressure Transmitter Calibration, installation and Certification.
• Temperature Transmitter Calibration, installation and Certification
• Temperature element calibration, installation and certification
• Flow computer calculations, ADC Inputs, master configuration lists.
• Product Automatic or Manual Sampling performance, installation, grab slippage, iso-kinetic flow check, ISO 3171 check.
• Laboratory – Karl Fischer Titration analysis, Sample handling, IP386 repeatability check.
• Calibration procedures, logbook entries, pipeline dispensations.
• Metering System Uncertainty calculations
• Metering System Management
• Training & Competency
• Previous audit routine and Frequency and Audit point addressing and close-out.

Environmental Audit

AMSPEC Provide a full Environmental Audit Service.

Environmental audits are now a requirement in many countries for any facility with emissions to the atmosphere, or discharge to sea.

The Metering Systems that are routinely audited are as follows:

• Flare Gas Metering (Example UK uncertainty of ± 7.5%)
• Fuel Gas Metering (Example UK uncertainty ± 1.5%)
• Produced Water overboard (Example UK uncertainty 30ppm oil in water).
• The Uncertainty requirements for these systems, is forever becoming more and more stringent each year and new systems should always be designed and adopted with this in mind, in order to future proof your system and eliminate expensive costs down the line.

A typical environmental audit would include the following:

• Flare gas zero report review, flare gas pipe diameter and wall thickness, installation, calibration report check.
• Fuel gas orifice plate inspection, orifice carrier inspection, meter tube installation & certification review.
• DP, Pressure and temperature calibration, installation checks and certification review.
• Chromatograph installation & calibration, pressure let down panel installation and operation, carrier and calibration gas certification review.
• Manual sampling
• Laboratory analysis.
• Daily reporting.

AMSPEC can Provide you with a full Metering System Inspection Service.

A metering System Inspection is normally done as a third-party inspection.

A Petroleum or Parent Oil Company may have subcontracted a service company or vendor to install a new Metering System prior to start-up or a new Green field or revised Brown Field Project.

The Petroleum or Parent Company will then hire a Metering Specialist company as a third party to perform a Metering System Inspection, to ensure that the work has been carried out as per the Functional Design Specification (FDS).

Just a small selection of some common problems during a pre-start up or commissioning Metering Inspection can be as follows:

• Incorrectly specified Instrumentation Ranges / Scaling
• Incorrect Calibration Certification and Non-traceable calibrations by factory non-National Standard Laboratory Calibrated Equipment.
• Incorrect configuration of Flow Computers and Supervisory Computer Software.
• Meter Tube, designed to wrong standard, AGA 3 instead of ISO 5167.
• Lack of system documentation
• Lack of certification
• Absence of Insulation and lagging for conditions of Service and Environmental location
• Lack of operational personnel training on the systems.

Metering System or Metering Equipment (FAT) Factory Acceptance Tests, are normally performed onshore, at the Vendor or Manufacturer facility, prior to a Metering System being shipped to its final operational location.

The Metering System Vendor will normally produce the FAT procedure, which will detail how the system is to be fully function checked against the Functional Design Specification Document (FDS).

Metering System FAT’s can be attended by a variety of representatives, petroleum or Oil company representative, Oil or Petroleum product pipeline representative, Metering System Vendor, Governing bodies and Third-party representatives to witness in an unbiased capacity for all parties & regulatory authorities.

All Metering System errors or discrepancies should be identified at this stage and then subsequently raised as punch list items, for the System Vendor or manufacturer to action, prior to final shipment.

Once all parties agree that the system is performing as per the FDS, only then should the system can then be signed off.

A metering SAT (Site Acceptance Test) is performed at the Metering Systems Final location.

The purpose of this Testing is to ensure that the system is fully operational and functioning correctly on site, at normal operational conditions and all to ensure there has been no damage or alteration of configurations etc during the transit period, which can in some case be months prior to arrival at site.

Metering SAT is required also to ensure that all pipework preservation methods have been adhered to in order to prevent environmental detrimental effects and exposure causing unnecessary corrosion or deterioration of equipment during transit to the end users’ site.

It is normal to experience problems with field wiring being incorrect, or communication problems as a result of Modbus or Communications protocols etc, due to interfacing between multiple vendors systems at site.

Pre-commissioning work is normally performed after system installation and sometimes in parallel with any metering SAT.

Metering Systems are required to operate within a regulatory uncertainty budget this can be set by Governing bodies, Pipeline partnerships and agreements that are based broadly on National or International Standards.

Uncertainty calculations are normally performed at the design stage of a Metering System, once the equipment has been selected and the operating and calibration philosophy has been agreed.

These are required to be documented and available at the metering system, as part of the system documentation, often requested for by metering auditors.

The uncertainty calculations may require to be recalculated during the life of the System especially if there are alterations or changes since inception, i.e. if new equipment is fitted or process conditions change from the initial parameters.

For Example, Gas Orifice Metering uncertainty is defined in ISO 5168 – Measurement of Fluid Flow Evaluation of Uncertainties. The metering system uncertainty takes in to consideration the accuracy of all meter instrumentation, ranges, maintenance frequency, system operation.  In addition, some external factors that may affect instrumentation such as ambient conditions and drift are also included.

A quick look at the implications of uncertainty.

A +/- 0.25% overall Expanded uncertainty for a Petroleum Liquid Metering System may seem a very small number, but has a large financial consequence.

As an example, a 100,000 bbl /day Oil Production equates to 36.5 Million bbl / year.  If this was operating at its limit of +/- 91,250bbls, this would equate at $80 USD per bbl to +/- $7.3M USD per year. If this was operational at double or more than this then you can see the magnitude of the financial impact.  Which is why we always strive to keep our measurement uncertainty to the very minimum possible to save the company losses that are completely unnecessary.

Metering systems can often operate at much higher uncertainties if operating at the lower range or bottom of their intended use. In this case it would be wise to re-evaluate the system and replace components that will reduce the uncertainty if necessary, to save on long term losses.

In a gas orifice system, as the field depletes, the meter tubes are often over-sized for the flow rates, the symptoms are low DP’s, as the accuracy of the DP transmitter is stated over full range, any errors in the transmitter operating at a much lower range will produce a much higher uncertainty in the DP component.