VIETNAM STANDARD: TCVN 6153-1995

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Safety engineering requirements of design, construction, manufacture Applying scopes: This standard has been applied for: Pressure vessels have working pressure which larger than 0.7 KG/cm2 Tanks, cylinders used for containing, transporting, LPG, or substances, which have working pressure larger than 0.7Kg/cm2 or liquid, powder or solid substances without pressure but when discard having pressure larger than 0.7 KG/cm2. Bottle used for containing, transporting LPG, dissolved gases which have working pressure larger than 0.7 KG/cm2....

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Nội dung Text: VIETNAM STANDARD: TCVN 6153-1995

VIETNAM STANDARD: TCVN 6153-1995 PRESSURE VESSELS Safety engineering requirements of design, construction, manufacture Applying scopes: This standard has been applied for: Pressure vessels have working pressure which larger than 0.7 KG/cm2 Tanks, cylinders used for containing, transporting, LPG, or substances, which have working pressure larger than 0.7Kg/cm2 or liquid, powder or solid substances without pressure but when discard having pressure larger than 0.7 KG/cm2. Bottle used for containing, transporting LPG, dissolved gases which have working pressure larger than 0.7 KG/cm2. Electricity boilers have working pressure larger than 0.7 KG/cm2 or electricity autoclave have temperature larger than 115oC. This standard doesn’t apply for: Vapor or water warming system. Vessel have volume smaller than 25 liters if P.V< 200. P= pressure (Kg/cm2) - V= Volume (liter). Cylinder of compressor and oil cooler, oil separator that accompanied with compressor systems, dampers… Non-metal vessels. Vessel contains water with high pressure but temperature of water smaller than 115oC or contains different liquids have temperature not exceed boiled point corresponding to 0.7Kg/cm2 Vacuum-vessel Steaming vessel use for manufacturing bicycle and automobile tires, Compulsory responsibilities of people concerning design, manufacture and using pressure vessels. Designers must have responsible for identify structure, calculation and selecting materials for each part of vessel, establishing diagrams of equipment, measuring, monitoring and safety devices that complying with this standard. In addition, designers have responsible for considering and agreeing these designing changes of manufacturers. Manufacturer must have responsible for setting up technology manufacture procedures in accordance with requirements of designers, organizing quality tests in each stage during manufacturing processes and also have responsible for their products’ quality according to designing and this standard. When selling products, manufacturers must grant these technical records for buyer as follows: History of vessel: 02 volume. Structural drawings of vessel have adequate main dimensions and nozzles. Manual instructions on erection and usage. Testing report after manufacturing. Technical documents must be maintained at least five years at manufacturing sites. The pressure vessel vendors must have responsible for the quality and the parameters of vessels at the working pressure that were announced in selling vouchers. Vendor must give warranty to vessel according to state laws and at the same time they must supply technical records according to article 4.2 of this standard. When the vendors lack of technical records in accordance with stipulation at article 4.2, they can ask personal or another agencies compiling technical records, but the vendor must have
responsible for the precision of this records. The pressure vessel owners must have legitimated responsible for management, maintaining and compensation the damage that created when have unusual events. The pressure vessel owners must promulgate stipulation responsible for person who directly or indirectly using the pressure vessels, at the same time they must well-implemented stipulation on inspection, registration of employing as well as enact the regulations, operating, repairing, maintaining procedures for pressure vessels. The pressure vessel operators have responsible for safety running pressure vessel as well as the substances that were contained in pressure vessel. The pressure vessel operators must pass the examination and were granted the operation certificate at working place. Refill substances operators must have responsible for identifying the perfect condition of pressure vessel before refilling as well as put forward safety precautions on transportation and using. Vendors that supply materials use for pressure vessel manufacturing and repairing must assure materials quality suitable with label and vendors must supply for clients mechanical and chemical compositions and properties. When these mechanical and chemical compositions and properties are not available, vendors must come to terms with clients and write on selling minutes. Measurable and safety equipment. General requirements: Pressure vessels inside this standard’s scope (exclude bottle) must be equipped measurable and safety equipment as follows: Measuring pressure. Safety devices The pressure vessels that have their wall’s temperature change abruptly must be equipped heating velocity measurable equipment, steady heating degree and stretching degree of pressure vessel’s wall. In the history of pressure vessel must supply degree of allowable heating and cooling. Each pressure vessel must stipulate capacity of filling and discarding substances in vessel. When condensing water and oil have probable accumulate in vessel, it is necessary to equip discarding equipment. Electricity boiler must be equipped feeding water pump and blowout valve. It is allow to replace feeding water pump by water piping system which have pressure higher than boiler’s working pressure, but not exceed 1.25 working pressure of boiler. The power of feeding water pump must at least equal 120% boilers’ output. Tanks and buckets must be equipped measurable and safety equipment as follows: Safety valve. Pressure gauge. Gauge-glass Valve use for filling and draining substances in vessel. Valve uses for air dismissing on the top of tank or bucket. This equipment must be attached on door, lid or comfortable position of tank or bucket. Tanks and buckets that contain liquid ammoniac have probably of evaporating up to 4 bar must be equipped: Pressure gauge. Two safety valves.
Gauge-glass. Nozzle with valve for taking specimen. Pressure gauge: Each pressure vessel must have at least 01 pressure gauge that suit with substance in vessel. Pressure gauge can be attached on vessel’s body, nozzle before stop valve or on control panel. It is not compulsory to attach pressure gauge when design pressure of vessel equal or larger than pressure of supplying source and pressure in vessel can not increase due to chemical reactions or temperature when supplying source have pressure gauge. Pressure gauge’s precision level must be not lower than 2.5. It is allowance to attach pressure gauge have precision level 4 when pressure vessel contains hydrogen which have temperature larger than 200oC. Pressure gauge’s surface must be drawn red line at working pressure. The range of pressure gauge must be chosen in order to working pressure fall on from1/3 to 2/3 of range of pressure gauge. Pressure gauge must be put vertical or lean forward 30o and protected from influence of high temperature or frost. Diameter of pressure gauge must be larger than 160 mm when distance from observer to pressure gauge is 2 meters to 5 meters. Pressure gauge must have three-ways valve or damper to protect pressure gauge. It is allowable to attach pipe that connect to pressure gauge has stop valve in order to attach the second pressure gauge replacing for thee-ways valve in pressure vessel has working pressure larger than 25 bar or substance in vessel is higher than 250oC, as well as vessel has toxic or explosive substance. Portable pressure vessel is not compulsory to attach three-ways valve. Pressure gauge must be calibrated and sealed 1time per year and after repairing at authority agencies. It is not allowance using pressure gauge in following cases: Having no seal and stamp of inspective agency and the due date Duration of usage expires. Indicator did not return original position when cut off air. Surface of pressure gauge be broken or another corrupt that have bad effect on precision of pressure gauge. Safety valve: Designers must calculate the number, dimension and exhaust capacity of safety valve on pressure vessel in order to prevent overpressure: 0.5 bar when allowance working pressure up to 3 bar. 15%p – when allowance working pressure from 3 bar to 60 bar 10%p – when allowance working pressure over 60 bar. It is forbidden to put lever safety valve on portable pressure vessel. It is not compulsory attach safety valve on vessel when working pressure of vessel is equal or larger than working pressure of supplying source and pressure in vessel cannot increase due to chemical reaction or different reasons . The structure of spring safety valve must assure as follows: Avoiding over-tighten spring. Protecting spring from high temperature and affection directly from substances Monitoring the technical circumstances of safety valve.
If safety valve work under substances (toxic, explosion) or requirement of technical processes, structure of safety valve can be omitted discard part. In this case, safety valve must be calibrated according to technology processes. 8.3.5 Safety valve must be put on the nozzle that was attached on vessel or on branch of nozzle in order to create favorable conditions for inspection. If there are many safety valve are put on branch of nozzle, cross sectional area of nozzle must be greater than 1.25 total of areas of safety valves. It is forbidden to draw active substance on the nozzle that connected to safety valve. It is banned to put the stop valve between vessel and safety valve. It is allowable to put shifting direction valve between vessel and safety valve with condition that in any position of shifting direction valve must be opened with safety valve. In this case, each safety valve must has enough capacity blow off following this standard. Safety valve of tanks and buckets must be pained in accordance with stipulation of that active substance. Safety valve of tanks that contain flammable gas must be painted brown color. Safety valve of tanks that contain inflammable gas must be painted black color Some another safety devices: Pressure vessel that has working pressure under source’s pressure must be equipped on the pipe from source to vessel one automatic reducing valve accompany with pressure gauge and safety valve put after reducing valve. We can put one reducing valve for pressure vessel group accompany with pressure gauge and safety valve before the first branch of pipe when a pressure vessel group which has the same working pressure. It is allowance to replace reducing valve as mentioned at article 7.5.1 by manual control valve enclose one safety valve and pressure gauge on low pressure in case due to the properties of active substances prevent the normal operations of automatic reducing valve. Substances that were discarded from safety valve must be lead to safety place. Nozzle from safety valve must has draining part. Each vessel must have automatic valve its function will dismiss pressure in vessel before open the lid. This outlet must be directed to safety position. It is strictly prohibited to open vessel’s lid when pressure still remains in vessel. Vessel has rapid blow-out valve also need equipping interconnection parts which help eliminate create pressure in vessel when close the lid incompletely and pressure still exist in vessel when lid was opened. Stop valves: It is necessary to put stop valve on pipe that lead active substance in or out vessel. It is allowable without stop valve between vessels when a group of pressure vessel was connected. Stop valve must has label. On the valve must has signals that indicate open and close on valve’s handle and the flow of substance on stop valve body. It is compulsory to equip automatic check-valve which can be closed by pressure in vessel on the substance’s pipe from pump or compressor to vessel which contain toxic active substance, flammable substance, explosive substance or substance vapors by high temperature. Check valve must be equipped between pump or compressor and stop valve of vessel. Gauge-glass Gauge-glass must be equipped at least one gauge-glass or another spirit level when pressure
vessel was warmed-up and its water level changes fluctuation. LPG cylinder must be equipped one gauge-glass or another spirit level to monitor maximum water level allowance. On gauge-glass must have two indicators: one shows maximum water level and another shows minimum water level and must has the comfortable structure for serving in cleaning, replacing, and always shows clearly water level in vessel.