Section 5 — Piping

IPE-EP-5-6-3

IPE Engineering Practice IPE-EP-5-6-3

Document number: IPE-EP-5-6-3 · Section: 5 — Piping

CoInafsletcatilo nA Prouinbta E nEgningeeirninege Prriancgtic Pesractices Piping for Fired Heaters 7.3.3 Where multiple fired heaters or other combustion devices are served by a common knockout drum (gaseous fuels), or supply header (liquid fuels), the individual supply line to each heater or other combustion device shall be provided with a manually operated block valve located at a safe and accessible point at a minimum of 50 feet from the equipment served. In this application, other valves can be used to meet the 50 feet requirement, however, they are limited to those provided in paragraph 7.3.5, items 3 and 4. 7.3.4 When practical, the block valve shall be grouped with the snuffing and purging steam valves. 7.3.5 Several valves provided elsewhere may satisfy the requirements in Paragraph 7.3.2 and 7.3.3 for emergency isolation valves. In addition to meeting the requirements of Paragraph 7.3.2 and 7.3.3 the valve’s closure must not create other hazards or conflicts with other actions that might be necessary during a plant emergency. Other required valves which may meet these requirements are: 1) Battery limit block valves (not to be used to meet paragraph 7.3.3). 2) Gas knockout drum inlet valve required in Paragraph 7.3.1 (not to be used to meet paragraph 7.3.3). 3) Filter station block valves. 4) The remote shut–off valve required in Paragraph 7.3.6, provided it can be manually operated. 7.3.6 In addition to the manually operated block valves required above, a means is required to remotely close (from the control house), a valve in each fuel line (excluding pilot gas) to quickly stop the flow of fuel to any firebox in an emergency. This can be accomplished by utilizing the shutdown valve in the main fuel lines or by motor operation of the valve required in Paragraph 7.3.2. This valve should be more than 25 feet from the equipment served. 7.4 (*)Piping downstream of the knockout drum shall, for Class I fuels, be steam traced and insulated to within 3 feet of the burner. When approved by the Owner’s Engineer, other forms of heat tracing may be used in this application. 7.5 Piping for individual burners shall be taken from the top of headers, except for a trash burner where one has been specified. 7.6 Piping for individual burners shall have breakaway connections (unions or flanges) located at the minimum practicable distance from the burner. These connections can be used for on line cleaning of the burners with steam. 7.7 All fuel headers shall have connections to facilitate cleaning before start–up or during downtime. All dead ends shall have blind flanges. 7.8 Fuel oil (heavier than 30 degrees API) piping shall be heat traced and insulated to the breakaway connection and insulated to the burner. Piping arrangement and insulation shall be designed for a maximum of 5°F fuel oil temperature difference between the first and last burners served by a common control valve under the following conditions: 1) Design flow rate. 2) Winter ambient conditions. 3) Assuming non–operation of the heat tracing. 7.9 Fuel oil valves for individual burners shall be located as close as practical to fuel oil header to minimize dead leg.

CoInafsletcatilo nA Prouinbta E nEgningeeirninege Prriancgtic Pesractices Piping for Fired Heaters 7.10 All pilots shall be gas fired. Where possible, the pilots shall have an independent pilot gas supply. 7.11 Process vessels discharging gas streams directly into fuel gas headers (no intervening drums) must be provided with a separate high–level alarm independent from the normal process level controller alarms. 7.12 For line sizes NPS 2 and larger, figure–eight or spectacle blinds shall be installed as indicated in Figures 2, 3 and 4. Smaller lines may be blocked for maintenance by opening and plugging but figure eight blinds may also be used. 7.13 The fuel system with a reliable and independent pilot gas supply shall be arranged as shown in Figure 2. 7.14 The fuel system with unreliable or common pilot gas supply shall be arranged as shown in Figure 3. 7.15 The fuel system for steam cracker and similar heaters with constant firing rate and no pilots shall be arranged as shown in Figure 4. 7.16 Pilot burner gas consumption, for use in sizing distribution heaters and laterals is shown in Table 1. 7.17 Provide plugged, threaded connection, NPS 3/4 minimum size, located downstream of last burner valve, for pressure gauges at each burner (for future field checking), on fuel gas, fuel oil, and atomizing steam, unless otherwise specified. 7.18 (*)Piping to the main gas burners shall normally be hard piped. Alternatively, a flexible metal hose assembly as shown in Figure 5, can be used with the approval of the Owner’s Engineer. The following criteria shall apply: 7.18.1 (*)The flexible metal hose for fuel oil and steam to an oil burner is required only for a small, easily misaligned burner typical of the natural–draft type of burner. Use of a flexible metal hose, and details of installation must be approved by the Owner’s Engineer. Guidelines for the selection of hose size, based on a maximum flow velocity of 75.0 fps at 15 psig, are given in Table 2. This limit is required to prevent bellows damage and noise. 7.18.2 Metal flexible hose shall meet the requirements of EP 5–4–4 and the following: 1) MAWP - 450 psig working pressure at 1200°F. 2) Hose Bellows - AISI Type 321 SS. 3) Braided Hose - AISI Type 321 SS with an outer layer of protective galvanized armor. 4) Bellows, braid and armor shall be attached to an AISI Type 321 SS Sch 80 pipe nipple on each side. 5) One end of the assembly shall have a Van Stone flange. 6) Metal Liner (if required ) - AISI Type 321 SS. 7.19 Position–indicating handles or pointers shall be provided for all plug or ball valves to indicate valve position. 7.20 Oil and gas block valve arrangement shall be per Figure 6 unless otherwise specified.

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