1. Information Required

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1 1. Information Required 1.1 Job Specification Job specification contains design criteria, agreed between Company and Client, affecting pipe rack design: Battery limit, valving and spade requirements. Catwalk, platform and ladder access to valves and relief valves in pipe rack. Minimum headroom and clearances under overhead piping or supporting steel within areas. Pipe ways and secondary access ways. Main access roads. Rail roads. Standard to be used for minimum spacing of lines in pipe racks. Handling and headroom requirements for equipment positioned under pipe racks. Operating and safety requirements affecting pipe rack and structure design. Location of cooling water lines underground or above ground. Trenched piping, if any. 1.2 Process Flow Diagrams Process flow diagrams show main process lines and lines interconnecting process equipment. 1.3 Engineering Flow Diagrams Engineering flow diagrams are developed from process flow diagrams and show: Pipe sizes. Pipe classes, and line number Valving. Mani folding. All instrumentation. Equipment and lines requiring services, i.e. water steam, air, nitrogen etc. 1.4 Utility Flow Diagrams Utility flow diagrams show the required services: Steam Condensate Water Air Gas Any additional services peculiar to the plant being worked on.

2 2. General The pipe way conveys all main process lines connecting distant pieces of equipment, relief and blow down headers, all lines leaving and entering the plant, utility lines supplying steam, air, cooling water and inert gas to the plant. Electrical and instrument cable trays are usually routed in the pipe way. Pipe ways are classified by their relative elevation to grade. 2.1 ABOVE GROUND:- a) Pipe rack:- Overhead piping supported on steel or concrete bents. b) Pipe track/pipe sleepers:- - Above ground piping supported on concrete sleepers at grade level. - This type of pipe way is generally associated with offsite areas where equipment is well spaced out, and land space is not a premium. - Wherever piping is laid on pipe sleepers, hard surfacing/gravel is provided below it, hard surfacing/gravel should be completed before start of pipe laying. Width of hard surfacing/gravel shall be about 1 meter more than the piping corridor on either side. This extra hard surfacing/gravel shall be for movement of operating personnel along the piping corridor. This movement area shall be approachable from the road at a distance of every 500 mtrs. Pipe track Width Pipe track width may be estimated using the method detailed for pipe rack. Spacing of Pipe track Sleepers Pipe track sleepers are relatively cheap thus piping economy is dictated by the recommended span of the smallest line in the track. Where small bore lines are few, sleeper spacing may be determined by the pipe span of large bore lines provided small bore lines are supported off the larger lines at adequate intervals. An angle with U bolts is sufficient (check with Pipe Support Section). For recommended pipe support spans, use Company standard. On an average minimum span = 3 meters Maximum span = 6 meters Depending on line size and substance carried in pipes, (i.e. gas or liquid). Pipe track Elevation Pipe track elevation is set by maintenance access to piping items located underneath the pipe track, i.e. drains and steam traps. A minimum of 12 /300 mm clearance between underneath of lines and grade is recommended; where necessary, this may be increased to 18 /450 mm. As pipe tracks are generally single tier, no change in elevation is necessary at changes of direction. This is affected by use of a flat turn.

3 Line Location Line location with reference to bore and weight is unnecessary, as all pipes are supported on sleepers which rest directly on the ground. Line routing is all important. All lines interconnecting process equipment and/or storage tanks located on left-hand side of pipe track are placed to the left-hand side. Similarly, all lines interconnecting equipment located on right-hand side of pipe track are placed to the right of pipe track. Lines interconnecting equipment located on either side of pipe track are placed near the centre of pipe track. Line Spacing Use Company job specification recommended pipe track spacing. Road Crossings The standard method is to provide culverts under access roads. Elevating piping on a cross-over rack is expensive and introduces unnecessary pockets in the lines thus routed. When determining width and height of culvert, care must be taken to allow sufficient room round the pipe work for maintenance, insulation and painting. Where only one or two lines cross a road, crossing may be by means of sleeves set under roadway. Access Ways In areas needing frequent access, platforms may be provided across pipe track. Valves Where possible, these should be grouped at the edge of an access platform for ease of operation. Drain valves where possible should be brought to outside of pipe track for ease of operation. The same applies to steam trap assemblies.

4 Expansion Loops Horizontally elevated expansion loops above pipetrack should be provided where necessary. Group all hot lines requiring expansion loops, hottest and largest line on the outside, on one side of pipetrack. (Generally, the side chosen is that side which has the highest number of take-offs serving equipment on that side). 2.2 UNDERGROUND:- The piping system is taken underground generally for the utility services like cooling water supply to various units and cooling water return to cooling tower for line sizes normally 18 inch NB and above, other water services with big pipeline sizes, big oil supply lines and various sewer systems in the process units of the chemical, petrochemical and refinery type of plants. The underground system consist of gravity flow drainage system carrying process waste, spillage, reclaimable hydrocarbons, sanitary and storm water, firewater and drinking water. a) Sewer Lines (1) Oily (2) Non Oily (3) Chemical (4) Sanitary Sewer b) Water Lines (1) Cooling Water (2) Potable Water (3) Sea Water (4) Industrial Water c) Fire Extinguishing Lines (1) Foam Extinguishing (at the time of Laying Piping) (2) Fire Fighting Water d) Trench (1) Electrical Cable (2) Piping for Process a) Trench Piping:- - Below ground piping laid in connection trenches. - Costly and usually undesirable; unless trenches are wide, shallow and well vented. - Heavy gases may settle and create a fire hazard through the length of the trench. For these reasons, only pump out lines, chemical sewers or chemical drain collection systems are sometimes placed in trenches and routed to a pit or underground collection tank.

5 In most plants, trenches are avoided due to problems associated with this type of pipe way: High initial cost. Fire hazard Trenchers are used to route lines such as: Pump out lines Chemical sewers Chemical drains Trenchers must be wide enough to allow sufficient clearance between trench wall and piping. 150 mm between outside of pipe and inside of wall is the minimum acceptable clearance. This will allow for installation of piping, painting and future maintenance. Total width of trench required may be determined by using method detailed above. Piping Department will advise Civil Department of requirements. Line Spacing Line location in a trench carrying a number of lines should be carefully chosen for maximum piping economy consistent with stress requirements, if any. Open trenches require drains to stop accumulation of surface water. Trench bottom should be sloped towards drain points. In this case, pipe supporting is by means of angle steel or I beams set into the walls, allowing bottom for free drainage to nearest drain point. This method allows drainage of a trench by a minimum of drain points between each pipe support as would be the case of solid concrete pipe supports built up from the trench. Before proceeding on trench drainage check with coordination procedure and Civil Department for water table level. Safety Precautions Most trenches have either a cover of concrete slabs or a grating. Where flammable liquids are carried in trenched lines, a fire break is provided at suitable intervals along a trench and at each intersection. This generally consists of two concrete walls 1 M M apart, with the space in between filled with sand. Where highly flammable gasses are carried, the whole trench, after installation of piping, is back filled with sand. Piping will advise Civil Department of requirements. Problems with Trenching Repairs generally require that a trench be opened for access. Many of these lines are far below grade and special precautions are required to ensure the safety of workers who enter these excavations. Sloping of trenches is usually only available on Greenfield sites. The trench slope is

6 laid back at an angle shallower than the angle of repose of the soil. This often requires a wide right-of-way. OSHA Standard for Trench pipe maintenance: (b) Employee safety and health training (a) Protect employees with shoring or sloping (b) Locate the utilities; contact the utilities (one-call system) (c) Provide egress from the trench or excavation (h) Protect employees from water accumulation in trench (j) Spoil pile or excavated material must be placed at least two feet from edge of excavation (k) Inspect trench or excavation on a daily or as-needed basis. b) Buried Piping:- - Piping direct buried below ground level. - Due to costly maintenance and the usually corrosive nature of soil, this method of routing is generally reserved for sewer and drain lines. - In some plants, especially in cold climates, cooling water lines are buried below the frostline. This should be determined at the beginning of a job, is generally a Client request. Keep buried piping to a minimum. Generally only sewer drain lines and fire mains are located below ground. In some cases due to Client or climate requirements, cooling water lines are also buried below the frost line. With future maintenance in mind, buried lines should be located well clear of foundations, and if running side by side, well spaced out. A minimum of 300 mm clearance is necessary between foundations and lines and between the lines themselves. Above ground safe drain-tails will enter below ground drain line via a tundish (concentric reducer normally) or if a sealed system and cooling water lines by a flanged stub raised above ground. Flanged connections should be a minimum of 300 mm above prevalent grade level. It is advantageous to set a common level for all these take offs at the outset of the job. When locating tie-in connections to underground systems, especially from elevated drain points, and adjacent to equipment plinths, ensure adequate clearance. All buried steel pipes should have applied a corrosion resistant coating and wrapping. Deep valve boxes for buried lines should be designed with ample room inside the box for a maintenance man to bend over and use wrenches for tightening flanges of re-packing valves. Consideration should be given to the use of concrete pipe in lieu of square boxes. The criteria for a good underground piping design should be ease of maintenance. Piping should be so spaced as to allow easy digging out and replacement of faulty sections; for this reason, never run underground piping under or through foundations. Pipe sleeves for underground piping Process facilities generally have pipe racks on which piping runs. These pipe racks allow the piping to be laid out over roads as well, leaving sufficient space for vehicles to pass below. But there are instances when pipe rack is not available at a particular location or it is not feasible to use pipe rack for piping. In such cases underground piping has to be done. In process plants cranes weighing up to more than 10 tons travel on roads. This load is born by the soil under roads. If we just dig a trench and lay the piping then every time when any heavy vehicle passes over that road, the pipe will also have to bear the load. In order to avoid any pipe leakage due to crushing load of the vehicle a pipe sleeve is used. Pipe sleeve is simply a pipe of heavy schedule

7 pipe and its size is approximately 2 to 3" larger. This sleeve is inserted such that load is now born by the sleeve and not the pipe itself. Under Ground Piping Basically the underground piping falls into one of two categories, process lines & drain lines. Process piping is probably the easiest routed enters the ground at point "A" and follows a routing that should be half way agreed on by the powers that be on the project by this time, and exits the ground at point "B" only issues are line spacing, burial depth, & corrosion protection on the pipe (if any). Drain piping is more complicated, this normally falls in two categories pressure drains, and gravity drains. Pressure drains are a "closed systems" that utilize pressure to push the commodity through the piping system. This piping is normally routed in the same trench with gravity drains. This is a "closed system" cleans out are not required in these lines, and this piping does not need to be sloped. Gravity drains are an "open system" that utilizes a sloped piping system so the commodity can get from point "A" to point "B" on its own utilizing the gravitational force acting on it. This "open system" means at points along this piping system there are branches to this piping that is open to the atmosphere to allow two things to happen, first and most important, this is where the waste commodity is introduced into the drain header. Secondly this is where the system is "vented" this allows the commodity to run down the system (kind of like putting a straw down into a container of liquid and putting your thumb over the end of the straw, with drawing the straw, the liquid will remain in the straw until you remove your thumb and the liquid is allowed to flow out of the straw, because the system (straw) was allowed to "vent", same thing on a gravity drain). Sloping drain headers - A gravity drain system is where the piping is sloped to utilize gravitational forces action upon it to get the waste commodity to where it can be properly taken care of or stored. Drain headers are normally run in there own trench with other drain headers. This is for a few reasons, first it is easier to slope the system if that has to occur with other sloped lines. Now pressure drains are routinely run with sloped gravity drains, normally because they end up in the same place (or close to it). Pressures drains don't require sloped piping, BUT it doesn't hurt that it is! Trying to slope some lines and not others in the same trench becomes a major construction headache so sloping the drains becomes the determining factor in the same trench, not only for engineering reasons, but only for a construction factor. This also dictates that any other buried lines that are routed with gravity drain will be configured using the 45 deg. ells. & a short spool piece between them, for any 90 Deg. change in direction (see this discussion in Clean-Outs) again because it is routed with gravity drains that do require this "unique" configuration. As I mention earlier sloped drain systems can get pretty deep over a long run, so it is advantageous to centrally locate the buried drain tank(s), ponds, or waste disposal area where the waste commodity eventually ends up, where-by shortening the drain system piping that enter this area. This does not mean dead in the middle of the facility! But off-set to the side, waste disposal is not normally the most important "system" in a facility, so it wouldn't occupy a prime spot in that facility.

8 Clean-outs these are the other branch connections on the main drain header. They are usually a 45 deg. lateral off the main header, & a 45 deg ell. in the vertical, and a threaded cap or a flange with a blind at the end. These clean-outs (C/O) are spaced approx. every 100 foot to provide a "port" so if the drain header becoming plugged maintenance people can go to this point, open up the port and introduces a "roto-router" (rotating blade at the end of a flexible cable) to be able to clear out the plug. This tool can normally reach about 100 ft., so positioning clean-outs ever 100 ft on the header is critical in case plugging does occurs deep in the drain header. This tool is very flexible and "could" make it through a couple 90 Deg ell., but the drain header needs to be designed to utilize this roto-router tool's flexible and not impede it, so all changes in direction on the drain header are done using 45 deg ell.s and not 90 Deg. ell.s (this helps the flow also). This configuration is also used in positioning/routing "drain funnels or drain hubs", this is because these points "could be" used to introduce this rooter-router tool as well, especially if the plug has occurred in that branch before the main header. A few design notes, as stated before, spacing for C/O's are approx. 100 ft., but there is another controlling issue, you don't want to try to push a roto-rooter through more then 5 fittings (this is a rule of thumb only) so a C/O would be required closer then the 100 ft. in this situation. One last clean-out location that needs to be discussed is the one on the very beginning of the main drain header. This is a configuration of 2 each 45 deg. ell.s in the vertical and a flange & blind (flg'd because of the larger size of the main header) could be a threaded cap on smaller drain headers. This is probably the most important one because it's the first entrance into the main drain header. It should be located where it can be easily accessed for maintenance equipment (all C/O's should be readily accessible!). An issue that can happen with all C/O's is "if" they could occur where there is vehicular traffic. Having a directly connected piping system exposed to traffic would cause stress/damage issues to that piping system. To eliminate this issue "covers" are fabricated to cover these C/O's. These covers have lids on them to be able to readily access these clean outs. These covers are basically a larger size section of pipe so you have 1" to 3" inches of clearance of any C/O flanges, this larger pipe would have 3 to 4 "lugs" welded to the inside and spaced roughly an 1" from the top edge so as a circular plate steel lid could be fashioned to just fit the inside bore of this "cover". A 1" diameter hole would be positioned into the center of this lid so the maintenance people could use a tool to remove this lid. Lid thickness to be able to with stand the traffic say around 3/8" to ½" thick. Design note - With the clean-out flange just fitting inside this cover, hex. headed bolts will have to be tackwelded to the underneath side of the flange so nuts are accessible from the top. Underground verses Overhead Piping:- The main criteria to be taken into account when deciding on the best design basis for pipe ways are economics, constructability, maintenance requirements and the process. Other aspects include the least interference to local or state amenities such as roads and railways, the minimum amount of interface and permit activities with local and state authorities and the protection of the local environment. The project will use overhead piping routes within the confines of the refinery to give ease of access for maintenance and fire fighting, to allow freedom of movement around the site without having to negotiate barriers created by low level pipeways and to give a more compact layout leading to economical piping design. Low level pipe ways will be used in offsite locations which in turn will reduce installation costs.

9 It is not considered good engineering practice to place hydrocarbon lines underground due to: * The detrimental effect to the environment in the event of a leak. * The widely differing effects on the piping stresses due to external forces. * Lack of maintenance access. Underground process piping is subjected to enormous external loads and material stresses due to thermal expansion, for example, a 12 sch 140 CS pipe operating at 100 deg.c would generate an anchor force of 500 tonnes over a distance of 1 km resulting in an anchor block, subject to soil conditions, of approximately 500 cu.m of concrete. Wall thickness usually has to be increased to compensate for the additional loads applied therefore increasing material costs. Additionally, piping would require external coating for protection against corrosion. It is not advisable to bury stainless steel lines close to shorelines due to the high risk of chloride attack from the saline conditions expected. External coating would be required but, this would be subject to damage during installation and friction due to thermal expansion. Cooling water and firewater piping are the only systems that are considered suitable to be buried due to the operating temperatures and very little or no thermal expansion.in the case of the cooling water system, the large sizes, due to their bulk, would take up a large amount of useful space. Large bore cooling water lines within the confines of the refinery complex will be buried but lines up to 30 may be located in the piperacks.generally, lines in the offsites and tankage areas will be above ground.however, it is essential that the extent of rock blasting is minimised and the philosophy regarding buried lines will be influenced by the results of terracing studies which will determine the cut & fill requirements. Firewater lines within the confines of the refinery will be buried but within the offsites and tankage areas these will above ground on sleepers. Effluent piping to the water treatment areas will be reviewed individually. Lines requiring a slope may be buried but lines being pumped will be placed overhead. Pipes should not be buried unless a clear-cut advantage can be gained. The main advantages of buried pipes are protection from freezing, fire, or accidental damage and these are valid reasons for burying fire mains or in exceptional cases, cooling water supplies if guaranteed flow under emergency conditions is essential. When pipes are buried, some general precautions should be taken Pipes should be below frost line or be buried to a minimum depth of 2 ft 6 in (0.75). Pipes passing under roads or access ways should be cased in concrete. If pipes run near roads or across cables, they must always be below cable level. Gas pipes should not be laid within 1 ft (0-3m) of plastic or asbestos potable water pipes. Provision must be made for valve chambers constructed in brick or concrete. Trench routes must be defined at an early stage in the job so that pipes clear foundations and the trenches can be dug during the main site civil works activity. Trench routes should not interfere with construction access. Full and accurate record drawings should be made of buried pipes for future use by the works.