Piping
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41. Paints and Painting
Paints are used for protecting the piping surfaces from corrosion. Paints are of different types. The type of paint to be used for a particular application depends on the environment and use. Paints have pigment and liquids. Paints are made from various chemicals. The pigments are ground to very fine particles. The pigments are in colloidal form in the paints. Usually the external surfaces of piping are painted. The internal surfaces are not painted, since they are not accessible for painting.
Primers are used for covering the surfaces before painting. Red oxide primer is commonly used. The following gives types of paints:
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1. Enamel paint
2. Anti-rust paint
3. Metallic paint
Distempers, available commonly, are cement based. Distemper is not commonly used for piping. The metallic paints are used for the edge preparation for the piping. These metallic paints save cost and time. Painting can be done using the following methods:
a) Wire brush painting
b) Spray painting
c) Dip painting |
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42. Detailing, Drafting and Documentation
Detailing involves the following activities:
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A) Edge preparation
B) Location of filed welds
C) Connection design
D) Checking for interface, interference, access, approach, walk-way and head-room |
Documentation involves preparation of Bills Of Materials (BOM), also known as Bills Of Quantity (BOQ). Documents required for procurement, fabrication and construction are also to be prepared. |
43. Fabrication and Transportation
The fabrication of piping is done considering the following aspects:
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1. Materials, shapes and sizes of piping
2. Welding and heat treatment requirements
3. Shop capacity, in terms of shapes, sizes and weights
4. Schedule and resources available |
The transportation of piping is done considering the following aspects:
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a) Transportation capacity, in terms of shapes, sizes and weights
b) Mode of transportation, like road, rail, ship, container
c) Field locations and shops locations
d) Load and size limitation of various transport routes, bridges and tunnels |
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44. Storage, Erection and Commissioning
The storage of materials should consider the products behaviors. The following storage methods are used:
A) In-door storage
B) Out-door storage
Erection and commissioning requires special skills and experience. As the erection and commissioning are critical activities, speed is the essence of any project. The erection and commissioning activities are part of the Critical Path in any project. Hence, good management and planning are required. Many computer based software are popularly used:
(I) Micro Soft PROJECT
(II) Primavera
The success of a project requires special skills, dedication and organization. The project manager, carrying-out the erection and commissioning activities, should have technical, commercial and management skills. Experiences in relevant fields are pre-requisites for successful completion of projects. |
45. Economics and Availability
Any industrial activity revolves around economics. Since the purpose of business is profit, industry always strives for economic design. Economics of a piping depends on the following:
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1. Pipe diameter
2. Pipe material
3. Pipe thickness
4. Insulation type and thickness
5. Refractory thickness and refractory material
6. Piping layout
7. Type of valves, gages, instruments and fittings
8. Supports and restraints
9. Loads and load combinations
10. Construction practices |
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46. Codes, Standards and Regulations
The words Codes, Standards and Regulations are inter-changeably used. But, in Engineering-applications these have specific meanings. These are used in industry to ensure safety of humans and property. The following are used for regulating and assuring safety of piping:
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a) Code
b) Standard
c) Regulation
d) Rule
e) Method
f) Guideline
g) Bill
h) Law
i) Procedure
j) Convention |
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47. Life of Piping, Failure and Maintenance
Life of industrial piping is about twenty-five years. But, the actual life of piping depends on the operating conditions and uncertainties of loads. The following affects the life of piping:
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1. Temperature excursions
2. Pressure excursions
3. Materials properties variations
4. Actual piping thickness
5. Actual variations in dimensions and behavior of associated equipment
The failure occurs when any one or combinations of the following happens:
a) Induced stress more the allowable stress
b) Induced deformation more than the allowable deformation
c) Induced vibration effects more than the allowable vibration effects
The piping requires periodic checking and rectification. The following are good practices to ensure proper care of piping:
A) Walk-down checks
B) Periodic inspection and rectifications
C) Preventive maintenance |
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48. Run or repair of Replace
A maintenance engineer faces a situation to decide whether to run or repair or replace the piping. This decision is critical in process plants and power plants. A process plant or power plant runs continuously for moths. Hence, when the plant is shutdown for preventive maintenance, several checks are made. The following gives a partial list of checks made during a planned shutdown: (I) Dimensional checks (Macroscopic checks), (II) Microscopic checks and (III) Destructive tests. |
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