The basis for determining the safe flow rate of media in pipelines

The flow rate is related to the static electricity of the liquid. Different media produce different static electricity.

GB 12158-2006|General guidelines for preventing electrostatic accidents. There are regulations http://www.bzfxw.com/soft/softdown.asp?softid=14251

Mainly related to pressure drop, it should be.

Thank you 3 hugs. I checked GB12158, which clearly stipulates the flow rate of hydrocarbons injected into the loading crane tubes of train tankers and car tankers, but there is no regulation on the injection flow rate for shipping. Moreover, the injection flow rate of hydrocarbons and the flow rate of hydrocarbons in the transportation pipeline should not be the same concept.

Relevant domestic and foreign standards regarding the safe flow rate of fuel products 1. API2003-1991 Measures to prevent ignition by static electricity, lightning and stray current 2.5 Highway tanker C. The initial flow rate should be limited to less than 1m/s； E. The filling speed should be controlled at the smaller of 7m/s and the value obtained by the following formula: v=0.5/d ； F. After loading or before sampling, the time should be maintained for at least 1 minute. ； G. For filters or screens with a pore size less than 100 μm (fine than 100 mesh), an electrostatic release time of at least 30 seconds must be maintained downstream. 2.7 Railway tank car 2.7.4 Control of electrostatic charge generation When the conductivity of the oil is less than 50 PS/m, v < 0.8/d, the rest also comply with the provisions of 2.5 3 Maritime operations 3.2 Control of electrostatic charge generation The initial loading speed is limited to less than 1m/s, and the loading speed can only be accelerated until the input port in the cabin is immersed in the oil for 0.3~2m. 4 Storage tank 4.2 Control of electrostatic charge b) Before the oil pipe is immersed in oil for 0.6m or twice the pipe diameter, the speed is limited to less than 1m/s ； d) Avoid large amounts of air or other entrained gases being pumped into the storage tank along with the liquid. 2. NFPA77-1993 recommendations on anti-static measures 4-3 Storage tanks 4-3.2 Protective measures (b) The filling pipe should be as close to the bottom of the tank as possible to reduce the turbulence of the liquid to a minimum. In principle, the injected liquid flow should be horizontal to reduce the impact on the water or sediment at the bottom of the tank. ； (c) Wherever possible, the linear flow velocity of the liquid flowing from the pipe mouth into the storage tank should be maintained at 1m/s, and the pipe mouth should be submerged below the liquid surface. ； (d) The water at the bottom of the tank should be drained as much as possible, because when there is an immiscible liquid (such as water) in the liquid flow or at the bottom of the tank, the electrostatic density or the amount of static electricity per unit volume will increase. ； (e) When pumping liquids into tanks containing vapor, entrainment of air and other gases should be reduced because air bubbles passing through flammable liquids can generate static electricity in the tank and release free charges on the surface of the liquid. 4-7 Tankers and Oil Tankers 4-7.2 Oil Tankers and Oil Tankers There is no cable connection between the oil tanker and the coast when loading and unloading oil in the oil storage ship and ship hold. 3. BS5958-1991 Anti-static Technical Specification Part One General Considerations 8 Static Electricity in Liquids 8.1.1 Single-phase liquid flowing in a pipe For liquids with very small conductivity and prone to static electricity hazards, there are some empirical relationships that can calculate the maximum current generated by the liquid under the condition of a long pipeline. The Schon equation is widely used.: is=Kv2d2 (K—constant, 4μAs2/m4). If expressed in terms of charge density, the above formula can derive the following approximate formula: η=5v, that is: When v=1～10m/s, η=5～50μC/m3. 8.1.2 Liquid/liquid and liquid/solid mixture flowing in the tube. When the mixed liquid is pumped through the tube, the process principle of static electricity generation is the same as that of single-phase liquid. Due to the increased contact area between mixed liquids, the rate of charge generation may be faster than that of single-phase liquids. However, it is not easy to calculate the rate of charge generation. 8.1.3 Fine particle filtration devices for liquids flowing through filters and filters can generate a large amount of static electricity. The charge density of the liquid leaving the filter is generally between 10 and 5000 μC/m3. 8.3.2 Controlling charge generation 8.3.2.1 Flow rate: When the liquid conductivity is low (below 50pS/m) and there are other liquid phases in the pipeline, a flow rate of 1m/s can be used to inject into the storage tank. In the initial stage of the perfusion operation, it is very likely that there is a second liquid phase. When there is no other liquid phase in the pipeline, it is not yet possible to determine the upper limit of the flow rate that should be adopted for all operations. According to current knowledge, the flow rate should not exceed 7m/s under any circumstances. 4. BS5958-1991 Anti-static Technical Specification Part 2 Specific Recommendations for Special Industrial Production 13 Ships (tankers) and barges 13.1 General instructions 13.2 Grounding operation methods Various liquid handling operations such as loading, measurement and sampling related to tankers and barges will cause fire hazards due to the generation of static electricity. To avoid these hazards, the recommendations given in Sections 13.2 to 13.6 should be followed. 13.2.2 Loading and unloading pipes between the ship and the shore are usually conductive. Conventionally, pipes are fitted with an insulating flange or a short length of non-conductive hose to prevent the risk of stray currents arising from the different electrical potentials that may exist between ship and shore. 13.2.4 It must be ensured that operators working near cargo holds do not create a fire hazard. If flammable mixtures are likely to be present, every effort should be made to prevent operators from becoming electrically charged. 13.3 Loading operation method 13.3.2 If the conductivity of the injected liquid is less than or equal to 50 pS/m, the bottom injection method or injection pipe used must ensure that all agitation of the unmixed liquid or sediment at the bottom of the liquid tank is reduced to a minimum. 13.3.3 If there may be unmixed liquid or sediment at the bottom of the liquid tank, when injecting liquid with a conductivity of less than or equal to 50 pS/m, avoid containing air or other gases in the liquid. 13.3.4 If the conductivity of the injected liquid is less than or equal to 50pS/m, before the injection port is covered, the linear flow rate of the liquid in the loading pipe must not exceed 1m/s. If a second immiscible phase occurs, such as water suspended in oil, it must always be maintained at 1 m/s. The maximum safe straight-line flow rate without the occurrence of a second immiscible phase has not yet been determined. However, experience shows that the flow rate limitations of current piping system designs are sufficient to ensure safe operations. There is currently no data showing that there is a danger when the flow rate is less than or equal to 7m/s. 13.4 Filters Fine mesh filters installed upstream of the cargo hold piping system may generate large amounts of electrical charge. Charges generated by filters should be handled in accordance with the methods given in the recommendations in Article 16. Note: 16.3 The regulations for the residence time downstream of the filter are: For liquids with conductivity (r) less than 2pS/m, the residence time should reach 3T (T≈50/r) ； For liquids with lower conductivity, T should be 100s. 5. AS1020-1970 South Australian Static Electricity Code 6.1.3 Factors affecting the generation of static electricity 6.1.3.1 Conductivity 6.1.3.2 When a large amount of contaminants are transported in a liquid, unlike the spraying or sputtering process, the rate at which the liquid generates static electricity depends on its conductivity, but there is no precise relationship that can be predicted. (a) Contaminants with high molecular weight will normally increase the generation of static electricity without effectively increasing the conductivity. This applies particularly to contaminants that dissolve as gums, such as rubber and asphalt ； (b) Entrained water: The presence of entrained water in clean unrefined or refined petroleum products will * * The trend of increasing the static electricity generation of products. 6.1.3.3 Fluid transportation speed and flow state 6.1.4 Static electricity generation trend of special liquids When the pipe diameter is constant, static electricity generation will increase with speed. The generation of static electricity can also be increased if, for example, rough tube surfaces or obstacles cause turbulence. It has been found that the net static electricity generation rate of diethyl ether and carbon disulfide is particularly high, while it decreases one by one for each of the following liquids:: Certain stupid homologues, gasoline, kerosene, other petroleum hydrocarbons, certain hydrogen chlorides, lipids, homologs and alcohols. 6.9 Avoid high flow rates 6.9.2 Hydrocarbons For non-conductive hydrocarbons, if the flow rate v (m/s) and pipe diameter d (m) can make v2d not exceed 0.64 m3/s2, it will limit its charging to a safe level. 6.20 Switching oil loading refers to the process of loading liquid into tanks or tanks pre-filled with liquids of different vapor pressures. Generally speaking, for liquids with roughly the same conductivity, static electricity generation will increase significantly. 15 Various processes related to liquids 15.4 Loading and unloading of oil tankers and barges Oil tankers and barges must be carried out in accordance with the safe implementation of petroleum standards and/or the relevant requirements of the American Petroleum Institute specification RP2003. 6. Static Electricity Safety Guide (Japan) 1988 2.2.2.2 Pipe transportation and filling (1) Prevent liquid from scattering (2) Limit the initial speed. In the initial stage of filling below, the flow speed in the filling pipe should be limited to approximately 1m/s. (a) When filling with a catheter, the front opening must be completely immersed in the liquid. ； (b) When filling from the side of the tank, the liquid should be one pipe diameter higher than the upper part of the inlet. ； (c) When using a suspended tank, make sure that the floating roof part completely floats on the liquid surface. ； (d) When insoluble substances such as water and air are mixed into the liquid in the piping, the insoluble substances must be completely discharged from the piping. (3) Limiting the maximum flow rate (a) The limit value of the maximum flow rate of flammable liquids with conductivity below 10-10S/m can be calculated by the following formula: ； The maximum value is below 7m/s. Assume σ=0.8pS/m, Table 2.1 is a calculation example for this situation. Table 2.1 Maximum flow velocity limit value Pipe inner diameter (mm) 80 100 150 200 250 Flow velocity when L≤2.9m (m/s) 4.8 3.8 2.5 1.9 2.4 Flow velocity when L≥7.2m (m/s) 6.0 4.0 3.0 80 4.8 100 3.8 6.0 150 2.5 4.0 200 1.9 3.0 250 2.4 (b) The equipment is often used within a certain range of conditions. If it can be used safely for a long time, the maximum flow rate can be determined based on experience, but the maximum flow rate should be limited to less than 10m/s. In addition, for liquids with conductivity above 10-10S/m, the maximum flow rate must be limited to below 10m/s. (4) Prevent the mixing of moisture, etc. When flammable liquids contain moisture and air, they will increase the electrification in the pipes and cause settling and floating charges in the tank. Therefore, the following measures must be taken to prevent their mixing (a) Before transporting the liquid, try to drain out the moisture, air, etc. in the pipes. ； (b) Drain the water remaining at the bottom of the tank as frequently as possible ； (c) When transporting with a liquid pump, do not suck air from the negative pressure part. (5) Microporous filter (a) The microporous filter should be installed as far upstream as possible in the piping to relax the electrical charge through the downstream (downstream) piping. In this case, the minimum required piping length at the downstream part of the microporous filter is calculated by the following formula: Z=3vε/k. When this length cannot be achieved, the liquid retention time (Z/v) in the pipe must be at least 30 seconds. 7. International Oil Tanker and Oil Terminal Safety Guide (Third Edition) ICS International Shipping Alliance OCIMF Petroleum Company International Maritime Forum IAPH International Port Association 7.4 Loading and unloading of static electricity storage cargo oil 7.4.2 Electrostatic storage Clean oil (distillate) is generally a static electricity storage body. Because of the low conductivity of this oil, the antistatic measures described in Section 7.4.5 may be required in some cases. Such oils include: Natural gasoline, kerosene, chemical petroleum solvents, power gasoline and aviation gasoline, jet fuel, naphtha, fuel oil, heavy diesel, clean diesel, lubricating oil. (a) In the initial stage of loading oil into each oil tank, the flow rate of cargo oil in the branch pipe shall not exceed 1m/s. After splashing and surface turbulence stop, the flow rate can be increased to the maximum allowable value according to the design of the ship type, shore pipeline and pump system, and at the same time, reasonable control of the oil transportation operation must be continued. If there is any issue with the oil delivery flow rate * * Level rules should be followed. (b) During oil loading and within 30 minutes after loading, no metal immersion parts, neutral measuring devices or samplers shall be immersed in the cargo oil in the oil tank, nor shall they be left in the tank. In general, non-conducting appliances may be used at all times with no metal parts attached. However, the rope used to attach the release device must be made of natural fibers and not man-made fiber materials. (c) It is well known that microporous filters made of pulp, cellulose or glass fiber can produce high electrostatic capacity. If this type of microporous filter is installed in the shore pipeline system, the loading quota should be strictly controlled so that the time between the cargo oil leaving the filter port and entering the oil tank shall not be less than 30 seconds. 7.4.5 Precautions when loading static electricity storage oil 7.4.6 Unloading static electricity storage oil 7.4.7 Unloading oil to shore oil tanks Since the air and/or bubbles in the liquid can generate static electricity, a stripping pump and a drainer should be used to avoid mixing air or oil vapor in the oil. Some additions need to be made to the provisions of the above sections, that is, when inputting electrostatic storage oil into shore oil tanks, the flow rate in the initial stage should be strictly controlled at 1m/s. Until the height of the oil layer in the tank has submerged the oil tank entrance without causing oil disturbance. For the side inlet (horizontal inlet) of the oil tank, the cargo oil has reached the acceptable level (no liquid disturbance) has passed through the inlet, which means that the distance between the top of the inlet and the surface of the cargo oil has exceeded 0.6m. ； For the down-bent inlet, it refers to the situation where the distance from the lower port of the pipeline to the cargo oil surface exceeds twice the inlet pipe diameter. ； For down-curved inlet pipes, a relatively larger distance is required to avoid liquid disturbance. For floating roof oil tanks, the flow rate in the initial stage should be maintained until the tank top begins to float. This provision also applies to internally floating oil tanks with fixed tank roofs. 8. GB12158-1990 General Guidelines for Preventing Static Electricity Accidents 4.3 Protection Measures for Liquid Materials 4.3.1 Controlling the Flow Rate of Hydrocarbon Liquids During Filling a. When filling railway tank cars, the allowable flow rate of the liquid in the crane tube is calculated by the following formula: vD≤0.8 b. When filling tank trucks, the allowable flow rate of liquid in the crane tube is calculated according to the following formula: vD≤0.5 where: v—flow rate ； D—Inner diameter of crane tube. 4.3.3 When filling large containers such as tank trucks with hydrocarbon liquids, oil should be fed from the bottom. If the oil is fed from the top as a last resort, the oil injection pipe should be extended into the tank no more than 200mm from the bottom of the tank. Before the oil injection pipe is immersed in liquid, its flow rate should be limited to 1m/s. 4.3.4 Other incompatible second-phase impurities such as water should be avoided in acetylenic liquids. And water accumulation in the bottom of the tank and pipes should be minimized and eliminated. When there is obviously a second phase in the pipeline, its flow velocity should be limited to less than 1m/s. 4.3.5 In large containers such as storage tanks and tank trucks, ungrounded conductive floating objects are not allowed to exist on the surface of flammable liquids. 4.3.6 When the liquid is highly charged, such as at the outlet of the fine filter, it can first pass through the moderator and then be output for filling. The residence time of charged liquid in the relaxer can generally be designed as three times the relaxation time. 4.3.9 When the accumulation of static electricity cannot be reduced by controlling the flow rate, a liquid static eliminator can be installed at the end of the pipeline. See Appendix D (reference part) for its structure. 4.3.10 When using hoses to transport flammable liquids, conductive hoses or rubber hoses with metal wires and mesh inside should be used, and attention should be paid to the conductivity of static electricity when connecting. 5.2 Safety management limits for electrified objects 5.2.4 When filling light oil products, the oil surface potential should be lower than 12kV. 5.2.5 The safe static conductivity of light oil products should be greater than 50pS/m. 9. GB13348-92 Static Electricity Safety Regulations for Liquid Petroleum Products 4 Basic Methods to Prevent Electrostatic Hazards 4.1 Electrostatic Grounding 4.2 Improving Process Operating Conditions 4.2.1 In the operation of the production process, oil products should be controlled to be within a safe flow rate range. Reduce oil splashing and prevent moisture and gas from being trapped in the oil (see GB12158). 4.2.2 Use metal pipes and components as much as possible. When non-conductive materials are used, corresponding measures should be taken. 4.2.3 Liquid petroleum products will generate a large amount of electrostatic charge when passing through the fine filter. There should be a 30s relaxation time from the filter outlet to the reservoir. 4.3 Use a static eliminator 4.3.1 In order to reduce the static electricity of liquid petroleum products, a liquid static eliminator should be used. 4.3.2 The static eliminator should be installed as close to the pipe outlet as possible. 4.4 Technical measures to prevent electrostatic disasters using antistatic additives 5.1 Oil tanks 5.2 Car tank cars 5.3 Railway tank cars 5.4 Oil tankers and ships 5.4.3 The initial oil loading speed is not greater than 1m/s. When the inlet pipe is submerged, the speed can be increased, but the 100mm pipe diameter is not greater than 9m/s ； The 150mm pipe diameter is not larger than 7m/s. 5.4.4 When loading oil, conductors are not allowed to be placed in the oil tank. After filling the oil, it should be allowed to stand for 10 minutes before using conductive equipment for sampling, temperature measurement, ruler inspection, etc. If the oil tank volume is greater than 5000m3, it should be allowed to stand for 30 minutes before operation. 10. GB16994-1997 Basic safety technical requirements for oil terminals 5.2.6 Anti-static 5.2.6.1 Oil terminals should be equipped with devices to eliminate static electricity on the human body at appropriate locations. 5.2.6.3 Anti-static design methods, measures and management should comply with the regulations of GB13348 and GB12158. 5.2.7 Prevention of stray current 5.2.7.1 When an oil delivery arm is used to load oil at an oil terminal, an insulating flange should be installed on the oil delivery arm. When rubber hoses are used to load and unload oil, a non-conductive short pipe should be installed on each hose line (the insulating flange and non-conductive short pipe are collectively referred to as the stray current prevention section below). 5.2.7.2 The lower limit of the resistance value of the anti-stray current section shall not be less than 25kΩ, and the upper limit shall not be greater than 2500kΩ. 11. SH/T3108-2000 Refinery-wide process and thermal pipeline design specifications 3.2 Determination of pipe diameter and flow rate 3.2.3 The design flow rate of process pipelines should comply with the following regulations: (1) In order to prevent fire or explosion caused by static electricity, when the conductivity of the oil is less than 50pS/m, the design flow rate of the oil pipeline should comply with the following regulations: aThe flow velocity of the inlet pipe of the light oil tank should be less than 4m/s. b The flow rate of light oil in the tanker loading pipeline should meet the requirements of Formula 3.2.1-1, and the maximum flow rate should not be greater than 7m/s. vd≤0.5 (3.2.1-1) where v——the flow rate of oil (m/s) ； d——Pipeline diameter (m). c The flow rate of the railway tank car loading pipeline for light oil products shall comply with the requirements of Formula 3.2.1-1, and the maximum flow rate shall not be greater than 7m/s. vd≤0.8 (3.2.1-2) d For oils with antistatic additives added, when the conductivity is greater than 50pS/m, or when a static eliminator is installed near the pipeline outlet, the flow rate can be increased, but it shall not be greater than 10m/s. e. When there is a filter net (the mesh number of the net is greater than 100 meshes) or a filter (the filtration accuracy is greater than 30 μm) before the pipeline outlet, the flow time from the filter outlet to the pipeline outlet should be greater than 30 seconds. f When the content of free water or pollutants in light oil is high, the flow rate should be less than 1m/s. 4. For liquid pipelines transporting catalytic oil slurry and other liquids containing solid particles, the medium flow rate should not be less than 0.9m/s. . 12. SH3097-2000 Petrochemical Electrostatic Grounding Design Specification 4.6 Pier 4.6.4 At the land entrance of the ship's position, a grounding device to eliminate human body static electricity should be installed. 4.6.5 To prevent stray current, the following measures should be taken: (1) On the oil delivery arm or oil pipeline, use an insulating flange or a section of non-conductive hose with a resistance value between 2.5×104Ω and 2.5×106Ω ； (2) The pedestrian passage between the ship and the shore cannot be connected with all metal ； (3) The wharf fender facilities and berthing ships should be insulated ； (4) The metal objects on the shore side can only be connected to the grounding device on the dock shore. 13. China Petroleum & Chemical Corporation Occupational Safety and Health Management System (1995) Chapter 2 Safety Technical Management V. Static Safety Management Regulations on Flammable and Combustible Liquids Article 5 When Class A and B liquids enter storage tanks and tankers, the initial flow velocity shall not be greater than 1m/s. When the inlet pipe is immersed 200mm, the flow rate can be increased, and the maximum cannot exceed 6m/s. The initial flow velocity of Category A and B liquids containing free water, organic impurities and two or more oil products shall not exceed 1m/s when mixed. For Class A and B liquids, the flow rate can be 6m/s after adding antistatic agents or having a special static eliminator and a static alarm device at the same time. When a filter is installed on the liquid delivery pipeline, there should be a 30s relaxation time between the delivery of Class A and B liquids from the filter to the loading. Article 12 In order to prevent the static electricity in the human body from causing electric shock or discharge, causing fires, explosions and other accidents involving flammable substances, the static electricity in the human body must be eliminated. Article 26 Grounding system of loading and unloading pallets and dock areas 4. There is no electrical connection (including jumper cables) between the pallet and the loading and unloading oil tanker and between the pipelines. Insulating flanges of 105 to 108Ω or insulating pipe sections should be installed on the oil loading pipelines. 14. GB/T15626-1995 Technical requirements for port loading and unloading of bulk liquid chemical products 4.2 Flow rate requirements 4.2.1 Throughout the loading and unloading of flammable liquids, the flow rate in the pipeline should not exceed 1m/s, and the flow rate in normal operations should not exceed 3m/s. 4.2.2 Other liquid products can use economical flow rates.

We generally design it to not exceed 3 meters/second. Only after reading the article on the 6th floor did we know that the initial flow rate must be limited. Thank you! It’s true that the ignorant are fearless ； It's too dangerous.

Thanks for the detailed introduction on the 6th floor. For oil tanks with internal floating plates, you should pay more attention to the initial flow rate.

Thanks for sorting it out on the sixth floor. study * one time