Piping System

The following DEP (Design and Engineering Practices) considerations states the high level requirement and recommendation the CONTRACTOR needs to consider in his process of development of Basses of design and consequently to be applied within all design activities relevant to piping system built in accordance to all types of process fluids and all utility fluids, Those considerations is intended for use in facilities related to gas, condensate & Liquified Petroleum Gasses (LPG) production, Gas handling, chemical processing and nodal compression units or may be used in any other similar facilities. The CONTRACTOR shall inform the principal of any deviation from the requirements of those guidelines due to any other obligatory reason.

I. Piping sizing

The CONTRACTOR shall consider the vulnerability to damage and limited mechanical strength for some defined sizes which is limited to special usages. After the basic pipe routes, number of valves, control valves, fittings, ...etc., have been determined, the anticipated pressure drop for the preliminary pipe sizes shall be checked. to be used in related to any calculation performed for pumping data.

Sizing of fluid piping systems

The sizing criteria depend on application. The function and application of the piping system will determine the sizing criterion to be selected. Where pressure drop is not a determining parameter, the size should be determined by the velocity constraints. As the velocities shall be kept low as possible enough to prevent problems with erosion, water hammer, pressure surges, noise, and vibration and reaction forces.

In some cases, a minimum velocity is required. When determining the velocity of the medium in the lines, account should be taken of the possible generation of static electricity. For design of piping systems where corrosion inhibition is anticipated, velocity shall be limited to reduce the effect of stripping the inhibitor film from the pipe wall.

Sizing of drilling fluid piping systems

The minimum flowing velocity of drilling fluid shall be calculated while prevent settling of sand in pipes. The maximum velocity in carbon steel should be considered to prevent cavitations/erosion on bends and damage to inline equipment and vessel internals.

Sizing of flare and vent systems

For sizing of flare, vent systems and relief valve inlet and discharge piping, Referring to Blow down and Flaring system guidelines which requires that the opening through all pipe and fittings between a pressure vessel and its pressure-relief valve shall have the area of the pressure-relief device inlet. The minimum flow area in the isolation valve shall be equal to or greater than the inlet area of the pressure-relief valve. In general, this requirement is satisfied by full bore, through conduit valves. The design of relief valve inlet and discharge piping and valves shall be adapted such, that the above requirement can be met.

General Considerations:

The following issues should be considered by the CONTRACOTOR in determining a suitable pipe size:

o The allowable pressure drop calculation

o Verify Whether pressure surges (for incompressible fluids) could occur in the piping system and to be evaluated with regard to the effects on the supports and the design pressure of the system. The designer shall ensure that the occurrence of a pressure surge can be tolerated.

o Verify Whether erosion could occur in the piping system.

o Verify Whether the piping system could be subjected to vibration.

o Verify Whether solids could settle out from the fluid (e.g., in slurry service).[

o The type of flow pattern in services where two-phase flow is possible, an

intermittent and unstable flow pattern shall be avoided.

o The allowable temperature drop if the fluid is highly viscous.

o The economic pipe diameter, considering the capital expenditure and operating

expenditure of the pumps, compressors and the piping system.

o Mechanical strength.[

o The required flow demand of the piping system or process (flow constraints).

o Weight constraints.

The above considerations shall be taken into account by the CONTRACOR for both the design conditions as well as for conditions such as start-up, shut-down and regeneration.

II. Piping Basics

Each different piping system such as boiler proper piping, boiler external piping, ...etc shall be designed, fabricated, erected, inspected and tested in accordance with its relative ASME B31.3. Piping shall be routed so that the optimum piping layout is achieved in terms of process requirement, ergonomics, commissioning, operation, inspection and maintenance.

Having considered these factors, the number of flanges, fittings, valves and welds shall be minimized. Span distances for support of straight pipe shall be in accordance with relevant code. Alternatively, other span distances are allowed when design calculations are provided, and the calculations show the alternate design to be acceptable in terms of the actual stress and deflection for the proposed installation.

The CONTRACTOR shall perform design reviews in stages to verify the proposed physical or 3D models to check that the arrangements meet the COMPANY requirements and to be accepted before proceeding with constructing phase.

III. Design Conditions

A piping system shall be designed by the CONTRACTOR for the most severe conditions to which it may be subjected with respect to preventing brittle fracture in metallic piping. The following may determine the design conditions :

heating medium pressure and temperature. surge pressure. pump shut-off pressure. static pressure. pressure drop. vacuum caused by cooling and possible condensing of trapped medium. steam/nitrogen purge pressure. boiler regeneration temperature. furnace decoking operation temperature. settling pressure of compressor. emergency depressurization. possibility of temperature rise due to stagnancy.

In situations where different design conditions exist in one piping system, different pipingclasses may be used and shall be divided by a spec. break and to be located so that the more severe design condition can never occur in the part of the system with the lower piping class and shall be executed as flanged connections. Dissimilar metal weld joints in some fluid services may be prone to premature failure or to significantly reduced useful life. A dissimilar metal weld joint is inherently a “lower integrity joint”, and the use of dissimilar metal welds has to be justified by solid technical and economic considerations.

Allowance for pressure and temperature variations shall be provided. Otherwise shall be subject to the approval of the COMPANY and shall only be considered in conjunction with a documented risk analysis showing the risk is managed. If an external pressure can only result from structural failure of equipment, failure of safety devices or other unpredictable events, it shall not be taken in consideration when establishing the design pressure of the piping.

Ambient temperature shall neglect the wind chill effect. Due consideration should be given piping subjected to “Shock” (e.g., rapid pressure rise). The effect of blast loads shall be evaluated for piping which is required to maintain the integrity in an explosion event.

IV. Piping Above Ground Level

Where practical, piping entering and leaving a plot area or a processing unit shall be grouped together. inside-plot piping shall be routed on overhead pipe racks. If the span between pipe supports is too long for the pipe size selected on the basis of hydraulic sizing criteria, the size of the pipe may be increased rather than providing additional pipe supports. This decision should be justified technically and economically.

Piping with instrument connections shall be routed so that safe access to these connectionsis ensured. If necessary, platforms or walkways shall be provided. Safety relief valve discharge piping shall be designed to withstand both the dead loads and the reactive or thrust loads. Reactive or thrust design loads shall take into account the most severe case, such as possible flashing conditions and liquid entrainment in vapor flows.

In a pipe rack, the following piping arrangements shall be considered:

The cryogenic pipe should be located at the sides of the pipe rack to provide spacefor expansion loops and to reduce the moments in the beams caused by the weightand thermal expansion loads from the pipe.

The cryogenic pipes should be grouped separately and located on different pipe racktiers.

Complicated crossings should be avoided, e.g., by not installing pipe rack spursopposite each other.

V. Clearance and Access

CONTRACTOR shall consider the vertical clearances relevant to minimum elevation of the bottom of overhead piping.

There shall be a horizontal clearance for access ways and walkways and thoroughfares. Piping shall be kept clear of equipment maintenance drop areas. Around manholes, a space for each side of the manhole and a minimum of space directly in front of the manhole shall be provided clear of obstruction to allow for entry and exit. Complicated crossings should be avoided, e.g., by not installing pipe rack spurs opposite each other.

The layout and arrangement of platforms, walkways and means of access thereto shall be such that the supervisory rounds can be made at various levels without requiring excessive climbing up or down.

Stairways are required for access to elevated work platforms, walkways and other elevated work areas where the frequency of use is at least once per shift.

Ladders may be provided instead of stairways where ladders are only required for occasional use, or for escape routes.

VI. Piping Below Ground level

VI.1. Buried piping

Buried piping shall be considered for drainage, storm water, sewage system, fire water and large diameter utility pipes so as not to impede traffic. And for pressurized hydrocarbon service, buried piping should be avoided. Buried piping shall have a minimum cover is soil to be considered according to the piping diameter and outside soil temperature and permeability.

The load on pipe crossing railways and roads should be equalized by means of pipesleeves or a culvert. The pipe shall be centered in the sleeves by use of distance pieces welded to the pipe, or distance pieces fixed to the sheeting if the pipe is insulated for low temperature service.

Insulated pipe should not be buried. If this is unavoidable, or if it is desired for life-cycle economic reasons, the insulation material shall be able to withstand the stresses caused by the thermal expansion of the pipe. Special attention shall be paid to avoid corrosion under insulation (CUI) and the system shall be designed so that inspection for CUI is possible or not needed.

Design of cathodic protection of buried pipe shall be considered in addition to the provide clear distance between the pipe and any electrical or instrument cables in case of piping operating.

VI.2. Pipe tracks and pipe trenches

Piping outside process units (e.g., piping between process units and storage facilities) should be supported on sleepers, at ground level in pipe tracks or below ground level in pipe trenches. The choice between pipe tracks or pipe trenches is dictated by technical and economic considerations, e.g., the number of road or rail crossings, the ground water level and the length of the required trench. Pipe racks may be used if space at ground level is limited or if the use of culverts or buried piping is uneconomical. The distance between sleepers in pipe tracks and in pipe trenches shall be based on the maximum allowed free span of the majority of pipes.

Flanged connections shall not be installed in trenches, in order to prevent the accumulation of gas and liquid vapors in the trenches. Flanged connections shall not be installed in enclosed trenches, in order to prevent the accumulation of volatile fluids in the enclosed trenches.

Concrete trenches in process units shall be adequately drained into a liquid-sealed drainage system and shall be covered with grating.

VII. Piping stress analysis and pipe supporting

VII.1. Piping Stress analysis

Piping systems shall be routed, supported, anchored or guided so that thermal expansion/contraction, weight effects including the pipe contents, insulation and any other superimposed loads, pressure effects, vibration or movements due to earthquakes and storms will not result in stresses in the piping or loads on the connected equipment in excess of those permitted by ASME B31.3 and the equipment design code, in order to prevent failure of piping components due to overstress, leakage at joints, excessive loads and moments on connected equipment.

The Pipe Stress Engineer shall determine whether local regulatory requirements of the country in which the plant will operate, have more stringent requirements than the codes and standards stated within this standard. In these instances, the local regulatory requirement shall govern.

Piping systems shall be checked for stresses caused by pressure, weight of pipe,equipment vibration, weight effects of piping components and fluids, external loadings such as wind loads, seismic loads, settlement, frost heave, thermal expansion and contraction, internal/external pressures, stiffness changes, enforced displacements and shock loadings.

Expansion loops and/or offsets shall be provided in piping systems where improvedflexibility is required. Expansion joints or swivel joints may be installed only where loops or offsets cannot be used (e.g., due to limited space) or will not give sufficient flexibility. Expansion joints or swivel joints shall not be used if the fluid fouling properties make them ineffective or will lead to leakage. Under special

circumstances, an expansion joint may be considered for other services provided that all alternatives without the expansion joint represent a greater safety risk. In all cases the proposed solution shall be accepted by the COMPANY.

The upper and lower design temperatures and differences in temperature between piping and equipment shall be taken into account for all design cases.

For piping connected to rotating equipment, pipe stress analysis shall be based on calculated piping loads on rotating equipment nozzles, pulsation and mechanical analysis. Actual piping forces and moments shall be qualified without taking the advantage of friction factor at pipe supports.

Pipe Stress Engineer shall identify and produce a formal listing of the critical lines to be analyzed using formal computer analysis. The purpose of the analysis is to calculate the thermal expansion/sustained or dynamic stresses, nozzle loads on the connected equipment and determine the type of pipe supports required.

VII.2. Piping Stress analysis condition

Temperature: Piping stress analysis shall be carried out for the temperature conditions such as Upper Design Temperature, Lower Design Temperature, Maximum Operating Temperature and Operating Temperature Transient conditions possibly caused by load cases such as start-up and shut down.

Pressure: Piping stress analysis shall be carried out for the pressure conditions such as design pressure, maximum operating pressure, operating pressure and cyclic pressure conditions.

Other condition shall be considered too such as frictional resistance to thermal movement effect, wind loading, seismic loads(earthquake loads), snow loads, sustained loads, blast loading and flare radiation.

At the completion of the project, stress reports shall be prepared for each system including the final versions of the Critical Line Lists, the stress sketch(es), and the Stress Analysis reports along with any changes made during construction or start-up. These reports shall become part of the Project documentation. The results of the piping stress analysis shall be documented as a report.

VII.3. Pipe supports

The span between horizontal pipe supports shall be selected in accordance with relevant standard Spans longer than those acceptable are allowed when justifiedby additional stress and flow induced vibration calculations. The additional calculations shall be approved by the COMPANY. Pipes should be supported in groups at a common support elevation.

Identification of standard pipe supports and special pipe supports shall be shown in the 3D model, on piping plan drawings and on piping isometric drawings. Supports and supporting structures shall be able to sustain the hydrostatic test load. If this is not economical, temporary supports may be applied. Spring supports shall be

blocked, or removed and replaced by temporary supports which are able to sustain the hydrostatic test load.

Weld-on attachments of the pipe supports should be welded to the pipe duringprefabrication of the pipe spools. The use of spring supports, snubbers and sway braces should be avoided. If they are unavoidable, they shall be permanently accessible. If this may lead to unacceptable costs, the COMPANY shall be consulted.

VIII. Piping Through walls, Structural decks and Concrete floors of buildings

Sleeves or holes through walls and floors of buildings and through table tops shall have a size permitting the passage of a flange of the relevant pipe size, or the size of the required insulation, whichever is the larger, to allow the installation of prefabricated piping.

Penetrations through walls and floors shall be sealed with a hydrocarbon-resistant filler after piping installation (e.g., a collar shall be fitted around the pipe) to avoid chimney draught in the case of fire. To prevent liquid dripping onto a lower deck, holes shall be provided with concrete curbs, cast-in extended pipes or other means.

The fire rating of the wall or floor including the penetration shall be maintained. Piping shall be routed to avoid penetration of major structural elements supporting decks and walls.

Penetrations through structural decks shall minimize the propagation of corrosion and stress concentrations. Flange clearance on piping that penetrates the ground or grating on an elevated work platform shall be in accordance with relevant design code.

IX. Seismic loads

If the region is susceptible to earthquakes, the anticipated earthquake loads shall beestablished. A piping system in an earthquake region shall have sufficient flexibility to absorb large movements without leading to excessive strain or failure. The following aspects shall be carefully examined and, where necessary, adequate measures shall be taken.

piping shall be provided with sufficient flexibility between two anchor points, takinginto account that the two anchor points may respond in different modes during anearthquake. piping offsets, expansion loops, etc., are normally only provided for absorbing thermal movements. Suitable limit stops shall be provided to restrict this movement in the event of a seismic shock.

supports for branch-off pipes and supports for vital control equipment shall bedetermined by careful scrutiny instrument lead pipes shall have sufficient flexibility to absorb seismic movements of the columns, pipe rack and/or structures to which the instrumentation pipes are attached.

piping going through bund walls, building walls and floors shall be provided withsleeves large enough to allow for the anticipated differential movements due toseismic loads. Dampening and sealing material shall be provided where it is required

to maintain a liquid tight connection.

X. Distance Between Pipes

The minimum distance between pipes shall be considered with relevant standard in addition to minimum distance between a flange (with/ without insulation) and a pipe or the insulation of a pipe in tracks, trenches and on pipe racks for tools access.

Where required, the distance between pipes shall be increased to allow for movementscaused by thermal expansion.

Adjacent flanges should be staggered, in order to minimize pipe space requirements.

Adequate clearance shall be provided for manifold piping and between hand wheels orwrenches of valves. Valves and flanges shall be staggered whenever possible to ease operation and reduce space.

XI. Small Bore Piping

Since small bore branches (≤ Diameter Nominal DN 40 (Nominal Pipe Size NPS 1 ½)) to large bore piping are relatively susceptible to failure, the following points shall be incorporated in piping design for avoidance of vibration induced fatigue of small bore piping and branch connections:

Minimize the number of small bore branches to piping.

Small bore piping, including its method of support, shall be shown in full detail, either on the isometric drawings or on a referenced document.

Branches shall not be located in removable spools, unless it is impractical to do otherwise.

Branches shall not be located in high stress areas.

The unsupported length of the branch and associated fittings should be as short as possible.

The mass/weight of the assembly should be as low as possible. Avoid installation ofheavy components (e.g., flanged valves) on the end of the connections.[

The distribution of the weight along the cantilever branch of the connection should bechosen to minimize reduction of the natural vibration frequency of such assembly.

Unreinforced branch connections shall not be installed immediately in the downstream of high capacity gas pressure reducing systems such as compressor recycle systems, steam desuperheaters, high-rate depressuring valves and safety relief valves. Also, for flow induced vibration, where the classification of susceptibility to failure is "high", special attention shall be paid to the bracing of these branches to the run pipe.

Maximize the diameter of small bore terminal connections. Connections on pipingbetween compressor and pulsation bottles and for all piping directly connected to thecompressor should be avoided. If such connections cannot be avoided, their sizeshould be maximized. The preferred size of a nozzles for branches is DN 80(NPS 3).

The bracing of complex geometries of connections or branches with heavy valve orflange weights shall be checked by a pipe stress engineer or vibration analyst.

In branches with flanged valves, branch fittings with flanged outlets shall be usedwherever possible, in order to reduce the number of welds.

XII. Installation of Flanges

Flanges in piping systems shall be installed only to facilitate maintenance and inspectionand where construction or process conditions dictate. For flanges in the following services, steam shall be used to control fires hydrogen service and flammable liquid services with operating temperatures at or above their auto-ignition temperature. Flanges shall not be located above main roads outside unit battery limits. Piping systems with Ring Type Size (RTJ) flanges shall be designed to allow removal of equipment and pipe sections without the need to remove very long sections of piping system.

For high pressure piping systems (ASME rating class 2500 or higher) connected to vessels, butt welded connections may be considered. Threaded blind holes shall not be used unless stud bolts cannot be used, especially in high temperature applications. Application of temperature resistant lubricants (anti-seize compound) is required in all applications.

Flange Joints in severe operating conditions include high pressure and high temperatureservices (i.e., above 450 °C (840 °F)), or in batch processes with rapidly fluctuatingtemperatures. To reduce joint relaxation in high temperature or cyclic service, spring washers may be installed under the nuts. As bolt relaxation mainly takes place during the first 1000 hours of operation, retightening may be needed soon after re-start. Care shall be taken not to overstretch the bolts. Flange joints shall be applied with maximum required torque and/or elongation. Checks, e.g., with turn of the nut method, shall be performed.

XIII. Installation of Valves

The number of different types of valves shall be minimized. All pipes entering and leaving the process unit shall have block valves and flanges provided to allow for spading (spades or spectacle blinds) at the boundary of the process unit ("battery limit"). The block valves shall be located near each other unless impractical.

A drain/vent connection shall be installed as close as possible to the block valves and spades, for draining, venting and testing purposes. Open ended valves in hydrocarbon or sour service shall be equipped with blind flanges or threaded plugs. Valves in horizontal pipes shall be positioned with their stem on or above the horizontal, except as follows:

Butterfly valves shall be positioned with the stem horizontal in services where foulingsubstances could collect in the lower shaft bearing.

Gate valves should be positioned with the stem horizontal in services where foulingsubstances could collect in the bottom cavity.

Valves shall be positioned with the stem horizontal in systems where a componentfailure (e.g., wedge pin) could cause closure of the valve and lead to unsafesituations (e.g., flare systems).

Pipes with wafer and/or plug type valves may require an extra flanged connection forinstalling a spade flange or removal of a pipe spool. Main block valves on branch piping systems should be arranged for self-draining on both sides, or provided with drain points at the block valve. Valves with extended bonnets in low temperature service shall be installed with stem vertical or a maximum stem inclination of 45° from the vertical.

Ergonomic aspects of valves

Valves shall not be installed above roads. Valves should not be located in overhead pipe racks. Valves requiring maintenance during normal operation, e.g., lubrication of plug valves shall be located so as to be easily accessible from deck, platform or permanent ladder. Gate valves should be positioned with the stem horizontal in services where fouling substances could collect in the bottom cavity.

Selection of gear drives for valves

Gear drives shall be selected in accordance with the applicable valve MESC SPEspecifications. The selection of motorized actuators shall be subject to the approval of the COMPANY.

Control valve installation

Globe control valves shall be installed with their diaphragm actuator stem in the verticalposition, with sufficient clearance above the actuator and under the bottom flange to allow the control valve to be dismantled without removing the valve body from the pipe.There shall be sufficient clearance to lift and remove the valve. Control valves shall belocated so that they are accessible for hoisting equipment where needed.

Manifolds for control valves

If required for operational reasons, control valves shall be provided with block valves and a bypass valve, except that a bypass valve shall not be provided in safety shut-off or depressurizing service or in applications where solids suspended in the stream may collect and block the bypass valve. As the provision of block valves, bypass valves, hand wheels, etc., is governed by operational considerations, the PFS and PEFS shall indicate the arrangement required for each application.

Body cavity relief (pressure equalization) provisions in valves

Depending on the process conditions and service application, for double seated valves in ASME classes ≥ 300#, the requirement for body cavity over-pressure relief has to beassessed on a case-by-case basis.

Equalizing of pressure around valves

Quick opening of a large valve holding high pressure may cause a significant shock wave travelling through the pipe at sonic speed. This can cause damage to vessel internals, flanged connections, bellows, etc. Since controlled opening (cracking a valve open) is easier with a small valve than with a big valve, large valves should be provided with a small by-pass in order to allow equalization of the high differential pressure.

XIV. Drain and Vent Connections

Minimum pipe wall thickness for vent/drain connections in carbon steel piping systems shall be maintained for butt welded and socket welded piping systems. Wherethreaded connections are allowed minimum wall thickness of threaded pipe nipples for vent and drain connections in carbon steel piping systems shall be maintained.

Drain and vent connections shall be installed, without valves, at all low and high points ineach piping system to facilitate venting and draining after pressure testing after construction or repair of the system. The location of the connections shall permit the complete removal of the test medium after the test.

If required for operation/maintenance, valved drain connections shall be installed at lowpoints, and valved vent connections at high points in piping systems. These connectionsshall be hooked up to a closed drain system. For drain and vent provisions on equipment. Valved vents and drains to atmosphere shall satisfy the double barrier concept. In this context, a blind flange on an outlet to atmosphere counts as one barrier. When threaded plugs or caps are allowed, the threaded plug also counts as one barrier.

Where process requirements demand a quick outlet to atmosphere, the double barriershall be obtained by installing two valves in series. If the effluent will flash andcause sub-zero temperatures, the distance between the two valves shall be calculated and the downstream (low pressure) valve shall be of the spring loaded, self closing type. The number of vent and drain connections with valves shall be minimized. The size and installation of process drains and vents shall be decided as a part of the process design.

XV. Connections for Manual Sampling

Dedicated connections shall be provided for sample collection. The sampling point shall be positioned so that the valves are easy to operate and taking the sample will not impair the safety of personnel or plant or cause environmental impact. The sample shall be maintained in a single phase Samples should be taken from a vertical pipe where possible. Sample take-off connections shall not be located at dead ends of piping. The length of thesample piping system shall be kept as short as possible to minimize purging.

For liquid sampling, the sample point should be placed in the 4 o'clock position and shall be positioned no further than the 5 o'clock position Sample take-off connections shall be easily accessible and should be at ground level and shall be connected to one common drain facility.

Sample points shall have two valves: one at the take-off point from the process pipe andanother at the sampling point. The block valve at the take-off point shall have the same size as a standard drain valve. The sampling valve size shall be maximum DN 15 (NPS ½) and shall have good throttling properties.

The outlet of a single sample connection, if not connected to a sample cabinet, shall eitherhave a male thread and be closed with a threaded cap, or it shall have a quick-fit couplingwhich seals when not connected to a sample receiver. Connections for hot samples (i.e., 80 °C (175 °F) or above) shall be provided with a permanently installed sample cooler. The PEFS shall indicate where a cooler is required.

XVI. Thermo well Connections

In pipes with turbulent flow, only thermowells with a length of 230 mm (9 in) should be used in order to reduce vibration and forces on the thermowell. In pipes with turbulent flow, the temperature difference between the centre of the pipe and near the pipe wall is

negligible so the shorter thermowell should not adversely affect the measurement accuracy. Thermowells should be avoided in pipes with two-phase flow.

As the vortex shedding frequency (also referred to as the Strouhal Frequency) approachesthe thermowell natural frequency, the tip displacement and stresses are greatly magnifiedand the thermowell can fail due to the large amount of energy it must absorb.

XVII. Orifice Flanges and Orifice Meter runs

When it is desired for the operation to install an orifice langes or orifice meter runs, flanges tapings, material and components for instrument connection should be considered.

XVIII. Displacer Champers

Displacer chambers for displacer type level instruments shall be considered. Loads on equipment nozzles caused by the weight and/or thermal expansion of displacer chambers shall be checked. To check the thermal expansion forces, it shall be assumed that the equipment is at design temperature and the displacer chamber is at ambient temperature.

XIX. Instrument Process Connection

Connections to piping for pressure instruments and Level connections shall be in accordance with the piping classes. Where threaded connections are utilized for installation of the pressure gauge, the ID of the piping upstream of the threaded connection shall have a restriction to limit the size of the opening in the event of threaded connection failure.

XX. Thermal Expansion Relief Valve (TERVs)

Thermal expansion relief valves shall be installed in liquid-full equipment or pipingsystems if the system can be blocked in and it is subject to heat from the atmosphere orprocess.

XXI. Cryogenic piping

For LNG loading lines, consideration should be given to the pressure drop of the line. Inorder to reduce the pressure drop of the flow and at the same time minimizing the boil of liquefied gas, the use of elbows shall be kept to a minimum.

XXII. Piping In Vibrating Service

All piping systems subject to vibration due to high velocity flow (where the classification ofsusceptibility to failure is "high" , high-pressure drop, water hammer or mechanical excitation are considered to be piping systems in vibrating service. Piping in vibrating service shall be screened according to Piping classified as “high” susceptibility category shall be further assessed and designed in accordance to Section 3 of the “Energy institute guidelines for the avoidance of vibration induced fatigue failure in process pipe work” or relevant recourse.

Piping subject to pulsating vibrations, shall be anchored and guided by means of heavyduty pipe clamps specially designed for this type of service. Designs with fillet welds shall be minimized. If fillet welds are unavoidable, instruction notes shall be placed on fabrication/isometric drawings requiring minimization of stress concentrators in the finished fabricated product.

Partial penetration welds or reinforcing pads shall not be used. Butt-welding components shall be lined up and weld roots shall be ground smooth wherever possible for inspection.

XXIII. Flow Line Design

Wellhead flow lines shall be subject to a formal piping stress analysis and shall satisfy therequirements of the relative ASME code. Consideration should be given to low temperatures, e.g., when opening up a high gas to oil ratio (GOR) well there is a considerable temperature drop across the choke valve. This may necessitate the use of special materials

To avoid erosion problems, flow lines shall use capped tees for safe degree changes indirection. Where flow-induced vibration is anticipated, or pressure drop is critical,consideration should be given to the use of certain radius bends. However, capped tees shall always be used for heavily erosive service, i.e., when sand production is expected.

For gas production flow lines where sand entrainment is a possibility, consideration shouldbe given to the inclusion of sand separation facilities within the flow line. For gas production flow lines which may be subject to high flow velocities, consideration should be given to the inclusion of high integrity erosion monitoring facilities within the flow line.

Flow Line Connections

In a typical Flow line configuration shall require a stress assessment whenthe pipe stress in the reducing fitting directly connected to the wellhead flow lineflange and/or Loads exerted by the flow line on the wellhead/X-mas tree joints (typically the flanged connections). The effect of lift-off of the first support downstream the wellhead/X-mas tree due to well thermal growth/shrinkage shall be taken into account in the determination of loads and stresses.

Flow line Pipe Support

Hangers and supports should not be welded to the flow lines and manifold headers. Flow lines shall additionally be supported and secured to minimize vibration and to prevent pipe dislocation. Dynamic load conditions to be anticipated in flow lines are, e.g., slug and/or hydrate formation.

XXIV. Retrievable Probe, Coupon and Injection Quill Systems

The use of intrusive erosion/corrosion monitoring coupons/probes and quills shall bejustified against alternative non-intrusive inspection techniques. Where retrievable erosion/corrosion coupons/probes and quills are still required, the retrieval strategy shall first consider retrieval from fully depressurized systems. If situations remain where it is not operationally possible to de-pressure the system, and online retrieval from pressurized

lines is justified, the design shall depend on tool type such as retractor tools of stuffing box, Pressure balanced retrieval tools or hydraulic retrieval tool, ...etc.

XXV. Piping Tie-in connections

Hot tap tie-in connection shall only be considered when both “Cold tie-in connection” and “Hot tie-in connection” cannot be executed on the existing piping system due to process operations limitations. Hot tap tie-in connections shall be considered within the restrictions. Hot tap tie-in connection usage shall be subjected to approval of the COMPANY.

The hot-tie-in connection branch shall be installed at 90 degrees to the axis of the run-pipe, preferably at the top of pipe location. Interference with the longitudinal weld seam of the run-pipe shall be avoided. The chosen location of hot tie-in connection on the run-pipe shall be checked and verified as suitable for the hot tie-in connection.

The supporting documentation for a tie-in execution (except for hot tap tie-in connections)shall consist of Design calculations for branch connection, Drawings The tie-in design package shall, as a minimum, include a general arrangement/isometric view to define the tie-in connection., Work procedures and final report

XXVI. Piping Adjacent to equipment / facilities

Piping and pipe supporting structures shall be designed so that access is provided formaintenance or removal of valves, in-line instruments, tube bundles and shell/channelcovers (e.g., cranes and trucks) and for operational reasons (e.g., filter cleaning). Removalor replacement of equipment shall be possible with a minimum dismantling of piping.Removable pipe spools may be required. Small pieces of equipment and ancillaries whichneed regular supervision or maintenance should be installed on elevated plinths in order toimprove access.

Piping at pumps, compressors and other equipments shall be sufficiently flexible andadequately supported to prevent the equipment nozzles from being subjected to any stressthat could disturb their alignment or internal clearances or otherwise affect the equipmentand jeopardize its operation.

Auxiliary piping shall be neatly routed along the base-plate and shall not extend across theoperating floor. This piping shall not obstruct inspection covers, bearing caps, upper halvesof casings or any other items which require access for operation or maintenance.

XXVI.1. Pumps

For pump selection, testing and installation, Suction piping shall be as short and as direct as possible, avoiding high spots where pockets of gas or air could accumulate As a minimum, the suction pipe and valves shall be same size as the pump suction nozzle. Each individual pump shall be provided with a strainer in the suction pipe.

A block valve shall be installed upstream of the strainer in the suction pipe of each pump. The piping components including the block valve to the suction nozzle of the pump shall have the same rating as the discharge piping in order to accommodate overpressure due to backflow from the discharge side.

The discharge pipe shall also have a block valve. A check valve shall be installed, unless there is no possibility of backflow or pressure surge under any conditions. This check valve shall be installed upstream of the block valve to enable maintenance of the check valve without draining the discharge pipe.

The liquid volume between the check valve and the pump discharge block valve shall be as small as practical. A vent or drain valve should be provided in situations where the check valve is not bolted directly to the isolation valve.

The bypass valve/piping should be considered with relevant to rotating equipment guidance. Pump vent and drain nozzles shall be fitted with isolation valves when connected to a common vent and drain systems and, if not connected to a drain system, the valves shall be fitted with blind flanges, or, where threaded connections are allowed, threaded plugs on the outlet side of the valve.

XXVI.2. Compressors

To prevent fatigue failure of compressor piping, the effect of vibrations and pressure surge shall be considered. Inter-stage and discharge piping shall be sufficiently flexible to allow expansion due to the heat of compression. Block valves shall be installed in the suction and discharge pipes, except for atmospheric air compressors, which shall have block valves in the discharge pipes only.

The block valve in the suction pipe, if present, and the piping to the suction nozzle shall have the same rating as the discharge piping. The ASME rating class of the suction piping, valves and suction pulsation dampeners (if fitted) of a reciprocating compressor shall have the same rating as the discharge of that stage.

Inlet and outlet strainers at compressor suction and discharge should be considered to protect against a blocked outlet. Compressors in hydrocarbon or very toxic service shall have: purge facilities, and Spading capability provided by spectacle blinds, removable spool pieces or elbows

XXVI.3. Heat Exchanger

Sufficient space shall be kept between adjacent heat exchanger inlet and outlet valvemanifolds. Shell and channel piping shall be provided with vent and drain connections unless it can be vented and drained via other equipment. Drain and vent nozzles on heat exchangers shall have a valve and a blind flange.

Piping connected to shell-and-tube exchanger channel box shall be self supported orprovided with permanent supports so that the channels can be removed without having to provide temporary supports for the piping. The piping shall be designed to provide wrench room for unbolting exchanger channels

Channel piping shall be arranged with a removable section between the exchanger andblock valves so that full access is available for bundle pulling and tube cleaning. Reboiler vapor return piping shall be free draining and drain towards the reboiler.

XXVI.4. Pressure vessel

Vertical pipes branching from columns and other vertical vessels shall have a restingsupport near the nozzle and shall be guided at regular intervals to protect the pipe against vibrations, wind load and/or buckling. If the loads on this resting support are too high, a spring support should be positioned at a lower elevation in order to reduce them. For the required flexibility of the piping, attention shall be paid to the location of the lowest guiding support.

Pipe supports on pressure vessels shall be bolted to cleats welded to the vessel. Cleats shall be designed by the CONTRACTOR and form an integral part of the pressure vessel. Where practical, cleats shall be standardized. Cleats and the connected pipe supports and/or supporting steel shall be designed so that there will be no ingress of water under the insulation. To allow removal of covers, heads, channels, bundles and shells, pipes shall not be supported on heat exchanger shells or heads

Pressure vessels that do not have a drain located directly on the vessel shall have a drain on the bottom outlet pipe. The drain valve shall be outside the skid. The size of the drain shall be in accordance with relative calculations.

XXVII. Level Gauges

Magnetic, glass, plate, Bull's and well types level are available and should consider the selection and design criteria for the process required application taking into consideration the design pressure and temperature and all other factors.

Drain valves on level gauges shall be accessible and shall be clearly visible from theoperator vantage point at access platforms and walkways. Level gauges shall be connected with block valves between them and the equipment. The pressure and temperature rating of the level gauge shall exceed or be equal to the pressure and temperature rating of the vessel.

The span of a level gauge shall cover the required operating range and the entire range ofother level instruments. If the required level range is too large for a single gauge, multiple level gauges shall be used, with the connection nozzles staggered for a visible overlap. Ifmultiple section gauge glasses are used, the visible length shall be the measured distancefrom the bottom visible portion of the lower gauge glass section to the top visible portion ofthe top gauge glass section.

The design and material selection of in-line instruments and control valves shallsatisfy the design conditions ((pressure and temperature) specified on the line list for thepiping system.

XXVIII. Utility Piping

The HC such as Condensate valved utility connections to atmosphere shall satisfy the double barrier concept. In this context, a blind flange on an outlet to atmosphere counts as one barrier. When threaded plugs or caps are allowed, the threaded plug also counts as one barrier. Where operational requirements demand a quick utility outlet to atmosphere, the double barrier shall be obtained by installing two valves in series.

Cooling water pipes ≤ DN 600 (NPS 24) should have block valves at the plot limit so thatthey can be isolated for maintenance while the cooling water system remains in operation. Large cooling water pipes may require special supports to avoid subsidence. Manual throttling valves should be provided in the main laterals serving each process unitfor flow balancing purposes. In addition, all exchangers except sample coolers shall beprovided with manual or automated throttling valves.

Backwash connections shall be supplied at water inlets to all critical cooling waterexchangers that are in process service. These shall be identified on the PEFS drawings.Such connections are sized to develop a high water side velocity in-tube, generallyrequiring a connection one size smaller than that of the supply line.

In elevated exchangers, where the cooling water return pressure is not adequate to provide sufficient driving force for back flushing, a jumper line (with valves) shall be provided from the cooling water inlet to outlet to facilitate backwashing.

Instrument air connections to process equipment or process piping SHALL be provided with two check valves upstream of a block valve with a vent to atmosphere located between the block valve and check valves. This provision will have minor increase in air consumption, but in case of backflow (leaking check valve) there is no driving force to blow small leakages past the most upstream check valve, as it will escape to the atmosphere.

XXIX. Tank Piping

Within the bunded area, the number of pipes shall be minimized and they shall be routed in the shortest practicable way from the tank to the bund wall. Where practical, the pipes shall be grouped together. Pipes connected to tanks shall be sufficiently flexible to cope with thermal expansion/contraction, tank settlement, the outward movement of the shell and the inclination of nozzles under hydrostatic load. Manifolds shall be located outside the bund wall.

Piping shall be connected after hydrostatic testing of the tank. Tank settlement, outwardmovement of the shell and nozzle inclination under full liquid load conditions shall be takeninto account when calculating bending moments and forces on tank nozzles. Pipingconnected to storage tank nozzles shall be provided with isolation valves.

XXX. Piping for Loading and unloading facilities

[Connecting pipes between the loading arms and the headers SHALL slope down to the headers for drainage. Where practical, the loading and unloading pipes shall slope down towards the shore for drainage.

XXXI. Piping Components

Components SHALL be selected from the applicable piping classes. The use ofspecial materials and/or piping components not included in the piping classes shall beminimized.

Metallic pipe shall designed with marginal corrosion allowance Welds requiring post Weld Heat Treatment (PWHT) shall be prefabricated as far as possible, thereby minimizing the number of field welds.. For Lined piping all flanged sections shall be hydrotested prior to coating.

Socket welded construction has been considered generally acceptable for the services conditions such as ASME B16.5 pressure classes 150 up to and including 2500, ISO 10423/API 6A Pressure Class 5000, General hydrocarbon service, H2S service, Amine service, Air, nitrogen and Water services (sweet, salt or brackish).The application of socket welded (SMAW, GMAW & FCAW, ...etc) fittings in piping systems shall always be subject to agreement by the Principal

The gasket selection SHALL be based on piping class requirements. For uniformity, and to prevent mistakes, all nozzles on a piece of equipment should be provided with the same type of gasket. The most stringent design condition shall determine the required gasket.

Selection and installation of bolting materials Shall be considered to be completely threaded. Nuts shall be semi-finished, heavy, hexagon. Nuts shall have a height equal to the bolt diameter. Coatings are applied to improve the corrosion resistance of carbon and low alloy steels when exposed to urban, industrial or surface marine (topside and splash zone) environments.

Fabricated fittings employing intersection welds may only be used in crosses, and shall be designed in accordance with the rules established in the relevant design codes orregulations. Short radius elbows have reduced allowable pressure ratings and require calculations to be made before utilization.

Isolation of equipment and pipes may be required carry out maintenance, safe entry of personnel, ..etc. From the process/safety requirement for isolation, the desired tightness and the desired speed of isolation can be derived. Single or double Valve isolation and Spectacle spades is the standard way of separating systems.

This type of isolation is provided in all cases where no specific tightness requirements are justified and where planned use of the isolation can be foreseen during the design stage. Where a bleed valve is provided, the purpose of the bleed is to verify that the isolation valve has seated and tightness has been reached before spading, and to provide a means of draining or depressurizing the volume between the spade/blind and isolation valve.

The configuration with double block valves upstream and downstream of the controlvalve with a capped/blanked bleed directly upstream of the control valve is normallyapplied.

Spectacle blinds and spades shall be located so that they are accessible from ground level or from platforms or walkways. The need for scaffolding shall be minimized.For easier handling, spading points should not be installed in vertical piping; if this isunavoidable, special precautions shall be taken to improve access and handling.

Valves are available in a wide variety of types, sizes, and pressure classes and are designed to perform. Valves shall be selected and designed based on a standard selection and one requiring a deviated selection due to the service. This can be the valve type and/or design. Each valve that passes validation testing will qualify a range of similar valves, based on design characteristics, temperature range, size, pressure class, fugitive emission class, and technical qualification class.

Ball, Plug, Gate, Globe, Check & butterfly valve types are the commonly used types of valves which shall be considered upon the process requirement and referring back to the Valve appendixes. The standard choice of metal seat facing material for all valves is Stellite 6. Tungsten carbide may be used for abrasive service. Triple offset butterfly valves utilizing laminated seats on the disc may use duplex stainless steel for the metal laminations. Since these components are basically in compression the normal maximum temperature can be extended from 300° to 400 °C (570 °F to 750 °F).

The prescription of packing types and materials has been discontinued. Valve stem sealing performance is not solely depending on the packing, but also on valve design (straightness, roundness, clearance, surface finish, tolerance and fit). Therefore, the packing material specifications are reduced to a minimum. If economically attractive to do so, valves may be repaired or reconditioned Valves shall be inspected when they arrive on site to verify that the following is in accordance with the purchase order.

XXXII. Thermal Insulation, Painting and Coating

On top of insulated columns and tanks, and over piping, where applicable, grating should be provided to avoid damage to insulation. Coating systems applied to stainless steel and (super) duplex stainless steel for the purpose of protection against corrosion (e.g., chloride stress corrosion cracking) shall be in accordance with relevant design code.