BN-EG-UE214 Preparation of Equipment Classification Lists for the PED Authority

Preparation of Equipment Classification Lists for the PED Authority

Table of content

1. Purpose

The purpose of this guide line is to describe how the equipment classifi­cation list, required for submission to Stoomwezen B.V in the Netherlands, shall be completed with relevant data.

2. General

2.1 Classification Lists

A general guide line on equipment classification lists for pressure vessel authorities is contained in ref. 6.4. It describes the process that should lead to conclusions regarding the required nature and level of pressure vessel inspection by authorities or designated third parties.

2.2 Pressure Vessel Authority for the Netherlands

The pressure vessel authority for the Netherlands is Stoomwezen B.V. This is the sole organization, that can approve and stamp equipment classification lists for Dutch projects. For piping, the classification is normally shown in the line designation tables; these are then subject to Stoomwezen B.V. approval in the same way.

3. Responsibilities

The Project Manager has the overall responsibility for the control of the prepararation and the approval of the classi­fication list for projects in the Netherlands.

The Project Engineering group has the responsibility for the preparation of the classification list for projects in the Netherlands.

The Authority Engineering group has the responsibility for checking the contents of the classification list, for determining the classifications and further handling of the list for projects in the Netherlands.

These responsibilities are worked out in more detail in ref. 6.4.

4. Guide Lines

4.1 Data Supply and Handling

Ref. 6.4 gives guidance for the supply and the checking of equipment classification list data and describes a number of handling aspects of this list.

4.2 Status of the Equipment Classification List in The Netherlands

The equipment classification list in the Netherlands is a document which requires formal approval by Stoomwezen B.V. for every issue. After approval, it is normally stamped for concurrence only, which does not imply responsi­bility for Stoomwezen B.V. for its contents.

Certain activities such as the submission of Stoomwezen application forms for equipment and piping can not start if there is no formally approved classification list.

4.3 Forms, Units, Language and Document Numbering

4.3.1 Basic Form
The handwritten basic form used by Company for a Dutch equipment classification list is shown in Attachment 3 of this guide line. The column numbers 1 through 21 have been added for easy reference. It shall be noted that the form deviates slightly from the requirements set forth in ref. 6.7.

Some clients (e.g., Exxon Chemicals) still prefer to use have their own basic form, even if not in accordance with ref. 6.7; such forms may have less or even more columns.

When a computerized form is used (for example, in dBase III software, see Attachment 4) a certain flexibility will be possible in the presentation and any deviations from ref. 6.7 can be agreed with Stoomwezen B.V. per project. Due to computerizing, the form can also be made suitable for other (internal) Badger purposes by adding further columns.

A completed version of a handwritten classification list is shown in Attachment 5.

4.3.2 Units
Pressures are indicated in "Bar" and understood as "Bar(g)", which equals Bar(abs) minus one. Full vacuum is indicated as '-1' (bar), although the use of the abbreviation 'FV' is not prohibited.

Older equipment classification lists often show pressures in kg/cm2. They can be converted to bar on a 1:1 basis while ignoring the difference between the units.

Temperatures are always given in degrees Celsius. Volumes are indicated in cubic meters (m3) or cubic decimeters (dm3). Densities, if filled out, are indicated in kg/m3; they are used for the hazard category calculations (ref. 6.5 and 6.8).

4.3.3 Language
The language on the equipment classification list is normally Dutch, but the use of English is accepted by Stoom­wezen B.V.

4.3.4 Document Numbering
For document numbering see ref. 6.4.

4.4 Details per Classification List Column

The column numbers refer to the manual form shown in Attachment 3. The computerized form misses columns 4, 12, 15 and 21 for space reasons or because they are less useful.

4.4.1 Columns 1, 2, 4, 6 and 21 (Equipment number, P&I diagram number, number of pieces, manufacturer, remarks)

The columns 1, 2, 4, 6 and 21 are self-explanatory. Column 4 is rarely used any more and, consequently, left out on the computerized form; instead, all individual items are listed.

4.4.2 Columns 3 and 5 (Registration Number, Serial Number)

The columns 3 and 5 must be advised by Stoomwezen B.V. after appro­val of the filled out data; both numbers serve administrative purposes.

Notes:

1. The Client may state his own serial number, but this number has to be approved by Stoomwezen B.V.
2. The registration numbers have to be obtained from the manufacturer's documents; these numbers are normally shown in the approval letter from Stoomwezen B.V. or the Nieuw Bouw Rapport (NBR) for the equipment.
3. A piece of equipment receives only one registration number, irrespective of the number of spaces the equipment has.

4.4.3 Column 7 (Substance and Phase)
In column 7 the names of the substances and their phases shall be stated. Mixtures should be described in sufficient detail for assessing the effects of each component (see also 4.5.3).

Notes:
For definitions of the phases: see Attachment 1 ("phase" is not identical with the concept "phase" in physics).

1. For vessels without tubes only the shell side data shall be filled out. 
2. For heat exchangers both shell and tube side data shall be given. Reactors etc. consisting of one shell with internal separation walls are considered as one vessel, the data shall be specified for all individual spaces because the classi­fication will be determined by the space with the highest requirements. In all these cases, an additional line per equip­ment item is required, because the majority of data will be different for the two (or more) spaces. For discussion of spaces, see Attachment 1.

4.4.4 Column 8 (Hazard Category)
In column 8 the hazard category shall be indicated. The hazard categories of shell and tube sides of heat exchangers as well as other indivi­dual spaces within the same shell may be different.

Notes:
For the hazard category calculation procedure, see ref. 6.8; for practical hints, see ref. 6.5.

4.4.5 Column 9 (Boiling Point at 1 Bar(abs))
In column 9 the boiling point at 1 bar(abs) shall be stated. For mixtures, the lowest temperature of the boiling range should be taken.

Notes:

1. For a sublimating solid, the temperature at which the sublima­tion starts should be stated.
2. The remark on mixtures refers to the most common type of mixtures, i.e. mixtures of liquids only.
   For other cases such as a solid/liquid mixture, the lowest temperature at which the liquid starts boiling should be regar­ded as the boiling temperature.
3. For special or complex cases, e.g. involving a decomposition reaction, the Authority Engineering group should be contacted.

4.4.6 Column 10 (Vapor Pressure)
Column 10 shall indicate the vapor pressure at the permitted temperature (see 4.4.10). For mixtures the vapor pressure is the sum of the partial vapor pressures of the components. The vapor pressure can never be higher than the set pressure of the pressure safety device protecting the equipment or equipment part.

4.4.7 Columns 11 and 14 (Normal Operating Pressure and Temperature)
Columns 11 and 14 shall state the normal operating pressure respectively temperature.

Notes:

1. These values should preferably in accordance with the process flow scheme(s), if these are submitted (see ref. 6.3).
2. Client's forms sometimes do not state this information.
3. For exchangers and other equipment with varying temperature either the range of temperatures should be shown, or the highest temperature only. Pressure variations can usually be ignored unless they are extreme.

Column 12 (Permitted Working Pressure)
Column 12 shall state the permitted (working) pressure. This is the pressure at which a piece of equipment may be used jointly with the installation in which it is placed.

The permitted pressure usually equals the pressure for which the equip­ment is protected, or, in case of a pump discharge without protection, the pump shut off pressure. The permitted pressure is the pressure which will be stated on the license.

Notes:

1. The permitted pressure shall be understood as "maximum possible operating" pressure. The word "permitted" is used from the view point of the license and in this sense, permitted equals allowable.
2. Newer types of the basic form, in particular the computerized ones, do not contain this column any more. The function of this figure (pre­venting that too high pressures will be licensed) is for most cases fulfilled by the design pressure. See 4.4.9.

Column 13 (Design Pressure)
Column 13 shall indicate the design pressure, which should be equal to or higher than the permitted pressure. The design pressure will be stated on the "Bewijs van Onderzoek en Beproeving"(BOB, certifi­cate of examin­ation and pressure testing), and is the pressure for which the equipment or the equipment part will be assessed by Stoomwezen B.V.

Notes:

1. If no permitted pressure is specified, the license will use the design pressure as such. By doing so, the often difficult discussion regarding the 'maximum possible operating pressure' is avoided.
2. The concept 'maximum possible operating pressure' is mainly useful for cases where the design pressure specification has other reasons than the process conditions only. An example are the design pressures for a Claus-type sulfur recovery unit.
3. For each single space only one design pressure should be specified (so, for a column no difference between top and bottom design pressure). Any static effects should be taken into account in the manufacturer's design calculations.
4. Ref. 6.1 and 6.2 should be applied when determining design pressures.

Column 15 (Permitted Temperature)

In column 15 the permitted temperature shall be indicated. The permitted temperature, which usually equals the maximum opera­ting temperature, is the temperature which will be stated on the licence.

Notes:

1. The permitted temperature shall be understood as "maximum possible operating" temperature. The word "permitted" is used from the view point of the licence and in this sense, permitted equals allowable.
   
   
2. Newer types of the basic form, in particular the computerized ones, do not contain this column any more. The function of this figure (preventing that too high temperatures will be licensed) is for most cases fulfilled by the design temperature. See 4.4.11.

Column 16 (Design Temperature)
In column 16 the design temperature shall be indicated, which should be equal to or higher than permitted temperature. The design temperature will be stated on the "Bewijs van Onderzoek en Beproeving" and is the temperature, for which the equip­ment part will be assessed by Stoomwezen B.V.

Notes:

1. If no permitted temperature is specified, the license will use the design temperature as such. By doing so, the often diffi­cult discussion regarding the 'maximum possible operating tem­perature' is avoided.
2. The concept 'maximum possible operating temperature' is mainly useful for cases where the design temperature specification has other reasons than the process conditions only.
3. For each single space only one design temperature should be specified (so, for a column no difference between top and bottom design temperatures). The effect on the wall thickness calculation is normally not large enough to enter into a long dis­cussion with Stoomwezen B.V. which may, at its conclusion, not lead to the planned result.
4. Ref. 6.1 and 6.2 should be applied when determining design temperatures.

Column 17 (Volumetric Capacity)
Column 17 should state the volumetric capacity for each space (e.g. shell and tube side). If not stated on the process data sheet this figure should be estimated based on - sometimes assumed - sizes, or, preferably, be obtained from the Vessel Engineering group.

All volumetric capacities should be verified with the manufacturer's documents as part of the regular updating of the classification list; this is particularly applicable to shell and tube heat exchangers and air coolers, with which the largest deviations from the estimated values are experienced.

Column 18 (Classification)

The Authority Engineering group shall determine the classification by means of Attachment 2 of this guide. The most common categories found are (1) steam or vapor equipment (either boiler or vessel - categories SK, DK, SV and DV) and (2) non steam-act pressure vessel (category DR). The classification is assessed for each space of the equipment.

The final classification is derived from the most severe set of design conditions for the different spaces; as a consequence, a water cooled heat exchanger can become classified as a 'vapour vessel' due to the conditions of the non-water side. See also 4.5.

The requirement for a license is usually determined by the Authority Engineering group; Stoomwezen B.V., however, may have a different opinion and will advise see by means of commenting on the classification list. The requirement for a BOB per condition of the Environmental permit should be determined by the Authority Engineering group.

For cases where a BOB is not possible (e.g. storage tanks) a BvK ("Bewijs van Keuring", certificate of inspection) or a VGB ("Verklaring van Geen Bezwaar", statement of no objection) can be requested.

Column 19 (Pressure Protection)
In column 19 the safety valves or rupture discs protecting a piece of equipment should be stated with set pressure and seat diameter. For rupture discs the nominal diameter and the nominal bursting pressure should be indicated.

Notes:

1. In the first issue of the classification list it is usually only possible to indicate the valve item numbers and the set pressures.
2. The set pressures and the back pressure of the safety valves need to be reviewed in an early stage of the project to avoid equipment design pressure changes in a later stage. For example, problems may occur when a safety valve in liquid service is located at some height above the protected equip­ment. See also ref. 6.1/6.2.
3. In practice, only the safety valves on or very near to the equipment protected are listed; more remotely located safety valves should be reviewed with the Authority Engineering group before listing (example : sometimes a safety valve for a vessel is located downstream a directly connected heat exchanger rather than up­stream of it; a survey of the complete circuit is then necessary to see what is protected by the subject safety valve).

Column 20 (Part)
In Column 20 the equipment part for which the data apply, should be indicated (e.g. for towers: top respectively bottom - see Attachment 4 gives an example). As noted above (see 4.4.9 and 4.4.11) this information is nowadays considered less useful. The computerized form does not contain a column to indicate the part, but if necessary a remark can be added.

Other Notes:
Equipment with More than one set of Operating Conditions

Equipment that may be subject to different operating conditions within the normal processing sequence (for example, regenerable reactors or vessels in multi-purpose plants) should be described with an additional line in the classification list. This will satisfy Stoomwezen B.V., that all possible operating conditions have been reviewed and that the final classification is in accordance with the most severe set of conditions found.

Equipment with Temporary Operating Conditions

Equipment with temporary operating conditions (for example, towers with steam out conditions) should only be marked as such, if these conditions may effect the classification. So, if the steam out pressure is limited to 0.5 barg or less, no separate mark should follow, because it does not change the classification nor does it cause Stoomwezen B.V. assessment or inspection work. Ref. 6.7 specifies the lower limits of this assessment or inspection work.

Temporary operating conditions should, in general, not be indicated on flow diagrams and similar documents, unless they are the result of a specific operational requirement and permanent provisions for their use (connections, controls etc.) will be installed. So, activities like regeneration, coke burning or run different processes in the same (or partially the same, such as for multi-purpose plants) installation are to be indicated on flow diagrams. Steaming out, on the other hand, is normally a maintenance activity, for which no permanent connection to the steam system is provided and should not be indicated on flow diagrams.

Special Requirements of Stoomwezen B.V.

In a number of cases Stoomwezen B.V. may comment on the design conditions chosen. This is e.g. the case with equipment, that is installed in the open air (thus, subject to the weather conditions inclusive of low temperatures) and can be put out of operation, but kept under pressure. The possible occurrence of such cases should be carefully reviewed during the early stages of engineering to avoid late comments and possibly material selection consequences. Other more or less frequent discussion points are the effects of substances such as hydrogen and hydrogen sulfide on the material.

Further Handling of the Classification List

The further handling of the classification list includes, amongst others, the following activities (see also ref. 6.4):

Checking for completeness.

Preparing for issue.

Submittal of issued classification list to Stoomwezen B.V.

Evaluation and incorporation of comments received from Stoomwezen B.V.

Updating the classificiation list with new and revised data.

Advising the interested parties such as the Vessel Engineering group and the Project Engineering group on comments affecting the equipment c.q. the requirements imposed on the manufacturers.

5. Flowchart

6. References 

Document

7. Attachments

1. Definitions of Terms and Concepts for use in the Netherlands.
2. Classification of Pressure Vessels in the Netherlands.
3. Basic form for manually filled out Classification Lists for the Netherlands.
4. Example of Computerized and filled out Classification List for the Netherlands (without columns for revision number and remarks).
5. Example of manually filled out Classification List

1. Definitions of Terms and Concepts for Use in the Netherlands

The following definitions are given to clarify the terminology of the classification lists for Stoomwezen B.V. and the underlying concepts. A detailed overview is given in ref. 6.6; the text below emphasizes the most important definitions in general wording.

1.1 Phases

Liquid: Any substance in the liquid phase.

Vapor: The gas phase resulting from the heating of a liquid; if the liquid is water, the vapor is commonly called 'steam'.

Note:
The liquid phase of a substance with a critical temperature equal to or lower than 45°C is never considered as heated; the gas phase of such substance can therefore never be a vapor, but is a gas. For heating see 2, below.

• Gas: Any substance in the gas phase other than vapor.

1.2 Heating

Steam apparatuses and vapor apparatuses are considered to be heated when the working temperature exceeds 45 degrees.

Note:
Heat transfer in such apparatuses at a working temperature above 45 °C always involves heating.

1.3 Pressure Vessels/General

• A pressure vessel is a technical device intended to keep up a pressure differential. This definition includes boilers.
  Note:
  This is a very wide definition; for further details and definitions used outside the Netherlands see ref. 6.5.
• The pressure section is that part of a pressure vessel that directly maintains the pressure differential.
  The pressure section encloses one or more spaces. It also includes the walls etc., that maintain a pressure differential between two spaces, as well as connected nozzles, flanges and fasteners. Supports etc., are part of the pressure vessel, but not of the pressure section.
• Appurtenances: technical devices serving to make possible the use of a pressure vessel or system or to promote its safe use.
  Appurtenances accordingly comprise valves, level indicators, pressure protection, pumps, pressure gauges, blow-off cocks, feed apparatus, controllers etc.

1.4 Pressure Vessels/Details

Steam boiler: An apparatus in which water is heated by heat supply which is not derived from another apparatus to which the Steam Act is applicable.

Note:
This definition would imply, that e.g. a waste heat boiler located downstream a reactor would generally be classified as a steam or vapor boiler, despite the fact that a waste heat boiler has rarely a boiler management system. This situation should, wherever possible, have an impact on the safety valve installation only and be limited for e.g. inspection terms by Stoomwezen.

Steam apparatus: A steam boiler or apparatus which is connected to the former in such a way that heat transfer takes place between the apparatus and the steam boiler by means of vapor or liquid.

Vapor boiler: An apparatus in which a liquid other than water is heated by heat supply which is not derived from another apparatus to which the Steam Act is applicable.

Vapor apparatus: A vapor boiler or apparatus which are connected to the former in such a way that heat transfer takes place between the apparatus and the vapor boiler by means of vapor or liquid.

Vessel: A steam apparatus other than a steam boiler or a vapor apparatus other than a vapor boiler.

Pipeline: A pressure vessel which serves mainly for the conveyance of substances; they may be split into (1) installation lines and (2) transmission lines, i.e. pipe lines connecting installations or facilities without being part of it.

Storage Tank: A pressure vessel intended for the storage of liquids below their atmospheric boiling point and not being part of a processing installation.

Note:
As a consequence, pressurized storage vessels (spheres, bullets) are not storage tanks.

Non-Steam Act Pressure Vessel: A pressure vessel which does not belong to one of the following categories:

• Steam or Vapor Apparatus
• Gas Cylinder or Transport Tank
• Storage Tank
• Pipelines
• Machine Parts
• Pressure Vessels containing solely a liquid below its atmospheric boiling point.

Notes

1. Vessels and non-steam act pressure vessels together cor­res­pond approximately to the English concept "unfired Pressure Vessels".
2. The above as well as other definitions are described in ref. 6.5.

1.5 Pressure Vessels/Separate Sections

The following shall be regarded as a separate section (space) of a steam apparatus or a vapor apparatus:

• A space which is neither directly nor indirectly connected to another space of the steam apparatus or vapor appa­ratus.
• A space which is connected to another space of the steam apparatus or vapor apparatus by means of openings in the common wall of the two spaces having a total cross­sec­tional area of passage not exceeding 20 cm2.
• A space which is connected to another space of the steam apparatus or vapor apparatus by means of pipes with an average length of at least ten times the diameter of the circle with an area equal to the total cross sectional area of passage of the pipes.

If the wall between two spaces is such that it must be expected to collapse when the working pressure is exerted on only one side, these spaces shall be considered together as a single space of the steam apparatus or vapor apparatus, irrespective of the preceding statements.

Classification of Pressure Vessels (Netherlands only)