Thursday, April 10, 2014
Posted by Ankit Chugh on 11:30 AM
Hey Guys, here i am back after a long break with something special for all my readers. I have getting frequent emails lately that they wanted to contribute to Piping Guide in some form. But i was so packed behind busy schedules that i was not able to reply to those queries instantly. So, here is something i have decided to do for my loyal readers.
Recently i have signed a NDA with an upcoming big EPC company who will be starting their operations in India very soon, might be in a month or two. Currently they are finalizing the office space and i am not sure whether they're going to finalize this in Delhi/NCR or in somewhere in sound India. And most probably, they'll be requiring nearly 200+ people at least in various departments. Hint: It'll be a company like Petrofac and they have a big project in their backlog.
Saturday, March 29, 2014
Posted by Ankit Chugh on 7:40 AM
It has been known for over 100 years that portland cement mortar and concrete provide considerable protection to embedded ferrous materials against the corrosive effects of soil and water. The most common embedded ferrous material receiving this type of protection has been the steel bars in reinforced concrete. There are literally thousands of reinforced concrete bridges, buildings, parking garages, and other structures in service today. During the 1920s practical methods were developed to apply portland cement mortar linings to cast-iron and steel pipe in the manufacturing plant. In the 1930s a method for applying cement mortar linings to in-situ pipe was developed.
Friday, March 28, 2014
Posted by Ankit Chugh on 12:53 PM
Assuming that methods for avoiding the need for tracing have been considered and rejected, the first step in matching the heat-tracing to the piping system requires an analysis of fundamentals. These include the type of application, suitability and relative cost of different types of heat-tracing, availability of steam and/or electricity, amount of heat loss which must be made up, requirements for temperature control, and classification of the traced area as a hazardous or ordinary environment due to the presence of flammable substances.
Areas are classified according to their potential fire hazard as defined by Articles 500 to 505 of the National Electrical Code (NEC).48 [In industrial applications, verification that electric components meet NEC hazardous-area requirements is issued by a nationally recognized testing laboratory (NRTL).] Under this system, there are classified and unclassified (ordinary) areas. Hazardous areas have two different classification systems, the old class/division method and the new zone system. The zone system has been used in Europe for many years and is now being included in the International Electrotechnical Committee (IEC) specifications. The old Class/Division system rates locations by class, division, and group. The area class determines the category of combustible atmosphere: flammable gases, vapors, or liquids (Class I); combustible dust (Class II); and combustible fibers (Class III). The division indicates the likelihood of a hazard to be present under different conditions. Hazardous atmospheres with similar combustion properties
are listed in the same group.
Friday, March 21, 2014
Posted by Ankit Chugh on 5:17 AM
Heat-tracing systems can be divided into two broad classes, electric and fluid. Fluid heat-tracing systems utilize heating media at elevated temperatures to transfer heat to a pipeline. The fluid is usually contained in a tube or a small pipe attached to the pipe being traced. If steam is the tracing fluid, the condensate is either returned to the boiler or dumped. If an organic heat-transfer fluid is employed, it is returned to a heat exchanger for reheating and recirculation. In general, heating of tracing fluids can be provided by waste heat from a process stream, burning of fossil fuels, steam, or electricity.
Electric heat-tracing systems convert electric power to heat and transfer it to the pipe and its contained fluid. The majority of commercial electric heat-tracing systems in use today are of the resistive type and take the form of cables placed on the pipe. When current flows through the resistive elements, heat is produced in proportion to the square of the current and the resistance of the elements to current flow. Other specialized electric tracing systems make use of impedance, induction, and skin conduction effects to generate and transfer heat. Table A lists the operating and exposure temperatures and the principal characteristics of the different types of heat tracing.
Posted by Ankit Chugh on 3:28 AM
The term heat-tracing refers to the continuous or intermittent application of heat to a pipeline or vessel in order to replace heat loss to ambient. The major uses of heat-tracing include freeze protection, thawing, maintenance of fluids at process temperature (or at pumping viscosities), prevention of fluid component separation, and prevention of gas condensation.
The following examples are typical of the diversity of heat-tracing applications: freeze protection of piped water; transfer of molten process chemicals such as phosphoric acid, sulphur, and p-xylene; low-viscosity maintenance of pumped fluids including petroleum products, vegetable oils and syrups, polymeric and resinous materials, and aqueous concentrates and slurries; avoidance of condensation and subsequent improper burning of fuel gas in refineries; preventing moisture from condensing out of piped natural gas; preventing freezing of control valves and compressor damage; elimination of pipeline corrosion due to wet hydrogen sulphide resulting from condensed moisture.
Heat-tracing may be avoided in situations where heat loss to the environment can be effectively minimized. In cold climates or areas with severe winters, water pipes are often buried below the frost line. Alternatively, they may be kept from freezing by running them through heated buildings.
In cases where flow is intermittent, tracing might be avoided by designing a self-draining system such as those used for steam condensate returns. Pipes may also be cleared after use by means of compressed air, steam, or solvent flushing or ‘‘pigging.’’ The self-draining method is suitable only for infrequently used pipes due to the high labor costs involved in cleaning and the potential cost and scope of repair, should a pipe not empty properly.
A third approach in the avoidance of tracing is to design for 100 percent flow. This practice is not recommended since equipment breakdown or process interruption may result in an irreversible drop in the temperature of the piped fluid.
Next Read - Types of Heat Tracing Systems
Next Read - Types of Heat Tracing Systems
Sunday, January 12, 2014
Posted by Ankit Chugh on 10:40 AM
ASME Code for Pressure Piping
Specific design requirements for piping support are included in the sections of ASME B31, Code for Pressure Piping, listed below:
● B31.1, Power Piping
● B31.2, Fuel Gas Piping
● B31.3, Process Piping
● B31.4, Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols
● B31.5, Refrigeration Piping
● B31.8, Gas Transmission and Distribution Piping Systems
● B31.9, Building Services Piping
● B31.11, Slurry Transportation Piping Systems
Wednesday, January 1, 2014
Posted by Ankit Chugh on 10:46 AM
The anticipated movement at each support point dictates the basic type of support required. Each type of support selected must be capable of accommodating movements obtained by one of the methods outlined later in this section. It is a good practice to select first the most simple or basic rigid support type and to add to the complexity only as conditions warrant. No advantage will be realized in upgrading a support when a simpler, more economical type can be shown to satisfy all the design requirements. Both vertical and horizontal movement must be evaluated.
Monday, December 23, 2013
Posted by Ankit Chugh on 2:45 AM
In practice, the assurance that the design and construction of a piping system will meet prescribed pressure-integrity requirements is achieved through the use of published codes and standards. Numerous codes and standards have been formulated and published by major interest groups of the piping and pressure vessel industry. The most widely used codes and standards for piping system design are published by the American Society of Mechanical Engineers. The American National Standards Institute (ANSI) accredits many of these codes and standards.
Sunday, December 22, 2013
Posted by Ankit Chugh on 10:15 PM
Design bases are the physical attributes, loading and service conditions, environmental factors, and materials-related factors which must be considered in the detailed design of a piping system, to ensure its pressure integrity over its design life.
Physical attributes are those parameters that govern the size, layout, and dimensional limits or proportions of the piping system. Dimensional standards have been established for most piping components such as fittings, flanges, and valves, as well as for the diameter and wall thickness of standard manufactured pipe. Those standards are identified in the section ‘‘Use of Codes and Standards in Piping System Design.’’
Monday, December 9, 2013
Posted by Ankit Chugh on 12:17 PM
The correct and economical selection of the supports for any piping system usually presents difficulties of varying degrees, some relatively minor and others of a more critical nature. Proper support selection should be the objective of all phases of design and construction.
Many pipe support problems may be minimized or avoided if proper attention is given to the means of support during the piping layout design phase. The piping designer’s familiarity with support problems, accepted practices, and commercially available pipe support components and their applications is extremely important.