FRP Laminate structure for pipe and fittings

Two standard manufacturing methods are used in FRP laminate construction as an overwrap for thermoplastic piping systems: Filament Winding and Contact Molding (hand lay-up).

Pipes and fittings of Type D, as per DIN 16965 / 966 standards, consist of a Chemical Barrier Layer (CBL) with a minimum thickness of 2.5 mm and a structural layer filament-wound from woven roving, Chopped Strand glass mats, and unidirectional woven roving. Additionally, there is a bonding layer that connects the thermoplastic liner to the FRP structure. The top layer serves as exterior protection and includes a resin layer with paraffin wax and UV protection.

Below figure shows CBL, Structural layer, top layer.

For Chemical barrier layer (CBL):  Chemical barrier layer consists of Resin-rich layer with a gelcoat veil and chopped strand mats. It is having resin content 75 ± 5% and Glass content 25 ± 5%.

Structure layer: This layer is the primary structural portion of the laminate and is designed to withstand the loads caused by pressure, wind, seismic and other conditions. It consists of alternating layers of chopped strand.

Structured layer for pipes: Filament winded from roving, Chopped strand mats and woven roving. It will have resin content 40 ± 5% and Glass content 60 ± 5%.

Structured layer for fittings: Laminated from Chopped Strand mats and woven roving. It is having resin content 45 - 65% and Glass content 35 - 55%.

Top layer / Outer Surface Layer: The top veil is used for protection against all weather conditions, UV radiation, and chemical reactions. If the outer surface of a laminate is to be exposed to a corrosive environment, a veil layer or a chopped strand layer may be added over the structural layer for additional protection. The outer surface can also be pigmented for color designation if necessary.

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Terminal Benefits of Construction Labour

Dear Readers,

Even though, the construction industry is the second largest employer in India, after agriculture. The casual nature of jobs in the unorganized construction sector can lead to poor working conditions, low salaries, and less job security. Construction projects are often located in remote sites, can be unpredictable, and there is a high chance of encountering unforeseen problems like weather. 

Terminal benefits are final entitlements of an employee upon termination of an employment contract. It is nothing but Money paid to an employee whose employment has been terminated because of a closedown or downsizing. 

Below Table shows the industrial practice of Terminal benefits for construction Workmen. A contingency has been included, which will be tailored to your requirements.

Please note that, if you leave the company on your own accord before the expiry of the notice period, you will not be eligible for retrenchment compensation as per the retrenchment notice already issued.

For costing, estimating, or rate analysis purposes, terminal benefit calculations are crucial to avoid significant crises. Calculating necessary cost provisions periodically and maintaining them can prevent financial crises and last-minute surprises.

For More Details about Basic Wages Click ABW

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Welding Terms Part-5 (I, J & K)

Dear Readers,

This is continuation of Part-4. This article will be a valuable resource for anyone looking to enhance their knowledge of the Welding Works.

Impact Test – A test in which one or more blows are suddenly applied to a specimen. The results are usually expressed in terms of energy absorbed or number of blows of a given intensity required to break the specimen.

IMPREGNATED-TAPE METAL-ARC WELDING – An arc welding process in which fusion is produced by heating with an electric arc between a metal electrode and the work. Shielding is obtained from decomposition of impregnated tape wrapped around the electrode as it is fed to the arc. Pressure is not used, and filler metal is obtained from the electrode.

Inclined Position – In pipe welding, the pipe axis angles 45 degrees to the horizontal position and remains stationary.

Incomplete Fusion – A weld discontinuity where fusion did not occur between weld metal and the joint or adjoining weld beads.

Incomplete Joint Penetration – A condition in a groove weld where weld metal does not extend through the joint thickness.

Indentation – In a spot, seam, or projection weld, the depression on the exterior surface or surfaces of the base metal.

Induction Brazing – A process in which bonding is produced by the heat obtained from the resistance of the work to the flow of induced electric current and by using a nonferrous filler metal having a melting point above 800 ºF (427 ºC), but below that of the base metals. The filler metal is distributed in the joint by capillary attraction.

Induction heating – Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, through heat generated in the object by eddy currents.

Induction Welding – A process in which fusion is produced by heat obtained from resistance of the work to the flow of induced electric current, with or without the application of pressure.

Inert Gas – A gas that normally does not combine chemically with the base metal or filler metal.

Infrared radiation – Electromagnetic energy with wavelengths from 770 to 12000 nanometers.

Intergranular Penetration – The penetration of filler metal along the grain boundaries of a base metal.

Intermetallic – A term used to describe a compound material composed of two or more metals or of a metal and a nonmetal.

Intermittent Weld – An intermittent weld, also called a skip weld, consists of a series of welds placed on a joint, with unwelded spaces between each of the welds.

Inter-pass Temperature – In a multi-pass weld, the temperature of the weld area between passes.

Inverter – A power source for welding machines that is much more efficient than the normal transformers.

Ionization Potential – The voltage required to ionize (add or remove an electron) a material.

ITP – Inspection Test Plan. (Similar to FQP). It's a plan that lists what tests and inspections should be performed throughout each phase of a project.

Jig – Jigs hold the metal or steel you are working on in place as you are fabricating. They can be steel clamped with a vice or C-clamp, bolts tack-welded to a table, or very elaborate frames.

Joined buildup sequence – The order in which the weld beads of a multiple-pass weld are deposited with respect to the cross section of the joint.

Joint – The junction of members or the edges of members that are to be joined or have been joined.

Joint design – The joint geometry together with the required dimensions of the welded joint.

Joint efficiency – The ratio of the strength of a joint to the strength of the base metal (expressed in percent).

Joint geometry – The shape and dimensions of a joint in cross section prior to welding.

Joint penetration – The minimum depth a groove or flange weld extends from its face into a joint, exclusive of reinforcement. Joint penetration may include root penetration.

Joint welding procedure – The materials, detailed methods and practices employed in the welding of a particular joint.

Kerf – The width of the cut produced during a cutting process.

Keyhole – A technique of welding in which a concentrated heat source penetrates completely through a workpiece forming a hole at the leading edge of the molten weld metal. As the heat source progresses, the molten metal fills in behind the hole to form the weld bead.

Kilogram (kg) – The kilogram or kilogramme (SI unit symbol: kg) is the base unit of mass in the International System of Units (SI).

kW (Kilowatts) – A kilowatt is simply 1,000 watts, which is a measure of power. Primary kW is the actual power used by a power source when it is producing its rated output. Secondary kW is the actual power output of a welding power source.