Feb 2010

The European Pressure Equipment Directive

This Directive applies to the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0.5 bar gauge including vessels, piping, safety accessories and pressure accessories. Not all pressure equipment is covered by this directive as The Transportable Pressure Equipment Directive and the Simple Pressure Vessels Directive both cover certain equipment and products which present a relatively low hazard from pressurization are covered by the Machinery Directive. The Directive defines a number of classifications for pressure equipment, based on their hazard level which is determined based on stored energy (pressure-volume product) and the nature of the contained fluid. Assessment and conformity procedures are different for each category, ranging from self-certification for the lowest (category I) hazard up to full ISO9001 quality management and/or notified body type examination for category IV equipment. Aspects of the design, production and testing of the equipment are the subject of a large number of harmonized standards to aid compliance with the essential requirements of the directive. Manufacturers must also provide adequate instructions with equipment, complete a specified declaration of conformity and maintain a technical file of information about how the equipment was designed and manufactured. Pressure equipment must be marked with the manufacturer, unique identification of model and serial number, the year of manufacture, maximum/minimum allowable pressure limits and the CE logo

Water in hydrocarbons has always been something to consider carefully in the oil industry and a common problem is water in crude oil. How it is measured or reported can affect either the buyer or seller financially. This may include:

• Custody Transfer
• Allocation
• Plant Balance (refinery input)
• Product Quality
• Sediment & Water
• Shrinkage (entrained gas)
• API gravity
• Contractual requirements 

A barrel of water, can cost considerably more than a barrel of oil. Someone has to pay for the oil, pay for the water, pay for the disposal of water and pay for the process contamination. Everyone is looking for a quick fix and even today we find contracts written around spot sampling which can be completely unreliable if the sample is non representative of the liquids in the process stream. The lab results are thus invalid and the frustration simply increases because the measurements unfairly affect someone’s wallet. Could this be your wallet?

Fig. 1.0 Separation occurs in oil/water processes and spot sampling using the above method misses “bottom” water.

Laboratory analyses are generally accurate but are quite useless if the sample being analyzed is not representative of the TOTAL FLUID FLOW

The same applies online. Fig 1.1 World class watercut meter measuring a non-representative distribution of water and oil. Inevitable and problematic watercut measurements ,arguments, doubts and wasted time and money.

Additionally we have problematic calibration if watercut meters are calibrated to lab results from non representative spot sampling. Spending the money on a highly accurate instrument that is not sensing at a point where we have a homogeneous mixture is an exercise in futility.

The problem becomes chronic as oil wells depressurize and watercut increases to the point when there is more water than oil being produced . In small pipes the chances of getting proper mixing in a higher watercut situation is doubtful and in large (greater than 6 inches) pipes it is a pipe dream. Honest field operators will be familiar with the problems of laboratory prepared spot samples for calibration never tallying with the reported watercut .

The only known solution is to mix, so that our sampling or watercut instruments are gathering samples or data in a volume area where sample is representative and homogeneous! Whether we are taking spot samples, grab sampling or installing watercut meters, the same will apply if we have an uneven or unpredictable water distribution in the crude oil stream. Manufacturers of static mixers have proved this fact time and time again over the years. There is adequate data to show that mixing should not be considered an option.

EESIFLO manufactures the EASZ-1 loop powered watercut monitors and inline static mixers and complete MBW systems which can incorporate any measuring instrument that we manufacture or the measurement instruments of your choice .The complete spool pieces can be fabricated and shipped and installed as a one piece system.
MBW systems are manufactured or fabricated in EESIFLO’s Singapore fabrication facility but can be supplied as a complete package through our global network

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