Piping Engineering / Design Blog.



Posted by Antony Thomas at Wednesday, November 23, 2011





• Used where the problem of corrosion is severe and it is difficult to get
a suitable metallic piping.
• Useful for handling corrosive or hazardous gases and dilute mineral
• Plastics are employed in three ways:
1. Plastic pipe.
2. Filled plastic materials (glass-fiber-reinforced, carbon filled etc.)
3. Lining or coating material.
• Temperature limitations restrict the use of these non-metallic piping.
• The commonly used materials are
2. FRP
3. FRV
4. PVC : Polyvinyl chloride.
5. Polypropylene,
6. GDPE,
7. LDPG,
8. ABS : Acrylonitrile-butadiene-styrene
9. CAB : Cellulose-acetate-butyrate.
10. Polyolefins.
11. Polyesters,
12. Cement,
13. Ceramic etc.


• Many plastics are not lanneable.
• Ultraviolet and other forms of energy can break the bond,
• Two Categories : Thermoplastic and Thermoset.
• Properties can be modified with addition of fibres, fillers, ultraviolet
stabilizers, coloured pigments and flame retardants.
• Most cost effective – unmatched in corrosion.
• High strength to weight ratio.
• Good thermal insulation.


• All glass piping is used for chemical resistance, cleanliness and
• Glass pipe is not subject to ‘crazing’ often found in glass-lined pipe and
vessels subject to repeated thermal stresses.
• Pipes, fittings and hardware are available both for process piping and
for drainage.
• ‘Corning Glass Works’ offers a Pyres ‘Conical’ system for process
lines in 1”, 11/2”, 2”, 3”, 4”, and 6” sizes (ID) with 450 F as the

maximum operating temperature and pressure ranges 0-65 PSIA (1”-
3”), 0-50 PSIA (4”) and 0-35 PSIA (6”).
• Glass cocks, strainers and thermowells are available.
• Pipe fittings and equipments are joined by flange assemblies which
bear on the thickened conical ends of pipe lengths and fittings.
• Corning also offers a Pyrex Acid-Waste Drainline system in 11/2”, 2”,
3”, 4”, and 6” sizes (ID) with breaded ends joined by Teflon-gasketed
nylon compression couplings.
• Both corning systems are made from the same borosilicate glass.


• To add mechanical strength with the corrosion properties of nonmetallic
materials, the concept of lining of material is established.
• Lengths of lined pipe and fittings are joined by flanges, and elbows,
tees etc are available flanged.
• Linings (rubber for example) can be applied after fabricating the piping
but pipe is often prelined and manufacturers give instructions for
making joints.
• Carbon-steel pipe zinc-coated by immersion into molten zinc (hot-dip
galvanized) is used for conveying drinking water, instrument air and
various other fluids.
• Rubber lining is often used to handle abrasive fluids.
• The combination normally used in the industry are:
1. Mild steel rubber lined (MSRL)
2. Mild steel glass lined (MSGL).
3. Mild steel Cement Lined.
4. Mild steel PP lined.
5. FRP with PP lined.
6. Mild steel PTFE lined.
• The requisition of lined pipes has to be studied case by case based on
the service conditions.

• These specifications are under the jurisdiction of ASTM committee F-17
on plastic piping systems.
• The standards are subject to revision at any time by responsible
technical committee and are reviewed every five years and if not
revised, either re-approved or withdrawn.




Posted by Antony Thomas at


• Vents are needed to let gas (usually air) in and out of systems.
• When a line or vessel cools, the pressure drops and creates a partial
vacuum which can cause siphoning or prevent draining.
• When pressure rises in storage tanks due to an increase in
temperature, it is necessary to release excess pressure.
• Air must also be released from tanks to allow filling and admitted to
permit draining or pumping out liquids.
• Unless air is removed from fuel lines to burners, flame fading can
• In steam lines, air reduces heating efficiency.


• After piping is erected, it is often necessary to subject the system to a
hydrostatic test to see if there is any leakage.
• In compliance with the applicable code, this consists of filling the lines
with water or other liquid, closing the line, applying test pressure and
observing how well pressure is maintained for a specified time, while
searching for leaks.
• As the test pressure is greater than the operating pressure of the
system, it is necessary to protect equipment and instruments by
closing all relevant valves.
• Vessels and equipment usually are supplied with a certificate of code
• After testing, the valved drains are opened and the vent plugs
temporarily removed to allow air into the piping for complete draining.



• Positions of the required vent and drain points are established on the
piping drawings.
• PIDS shows only process vents such as vacuum breakers and process


• Quick opening vents of ample size are needed for gases.
• Safety and safety-relief valves are the usual means.
• Gases which offer no serious hazard after some dilution with air ma be
vented to atmosphere by means ensuring that no direct inhalation can
• If a combustible gas is toxic or has a bad odor, it may be piped to an
incinerator or flarestack, and destroyed by burning.
• Air has a moisture content which partially carried thru the compressing
and cooling stages.
• It is this moisture that tends to separate, together with any oil, which
may have been picked up by the air in passing thru the compressor.
• If air for distribution has not been dried, distribution lines should be
sloped toward points of use and drains : Lines carrying dried air need
not be sloped.
• If the compressed air supply is not dried, provide:-
1. Traps at all drains from equipment forming or collecting liquid –
such as intercooler, aftercooler, separator, receiver.
2. Driplegs with traps on distribution headers (at low points before
rises) and traps or manual drains at the ends of distribution



Hydrostatic Test Vents and Drains –Guidelines

Posted by Antony Thomas at Tuesday, November 22, 2011


(a) Hold a recognised qualification in engineering draughting, CGLI or equivalent

(b) Have at least ten (10) years of practical experience as a designer in the specific discipline of which at least two (2) years shall have been spent in the overall coordination of a multi-discipline design office in the offshore and onshore oil and gas industry.

(c) Be experienced in the Quality Control, requirements and general management of a multi-discipline design office.

(d) Duties shall includes: preparation of manhour estimates, detailed planning and scheduling for the draughting work to be carried out

• Preparing sketches/proposals for the designers and draftsperson to develop into detailed design drawings

• Preparation of process of flow scheme (PFS), process and engineering flow scheme (PEFS) cause and effect matrix, logic diagrams, general arrangement drawings, layouts, isometrics, etc,; and will be expected to carry out checks on the drawings produced by his section

• Make basic design calculations and must be familiar with both industry and Shell Standard and should have a sound working knowledge of Computer Aided Draughting (CAD), AutoCAD techniques, INTools, and be responsible for directing and coordinating the work for CAD

• Supervision of the training/development of new trainee draftsperson and students.

(a) Hold a recognised qualification in engineering draughting, CGLI or equivalent and have at least seven (7) practical experience as a designer in the specific discipline in the offshore and onshore oil and gas industry.

(b) Be knowledge in the Quality Control, requirements and general management of a multi-discipline design office.

(c) Duties will include the following types of work:

• Capable of preparing sketches/proposals for the designers and draftsperson to develop into detailed design drawings.

• Fully understand the preparation of process flow scheme (PFS), process and engineering flow scheme (PEFS) cause and effect matrix, logic diagrams, general arrangement drawings, layouts, isometrics, etc.; and will be expected to carry out checks on the drawings produced by his section.

• Required to make basic design calculations and must be familiar with both industry and Shell Standards and should have a sound working knowledge of Computer Aided Draughting (CAD), AutoCAD techniques, INTools, and be responsible for directing and coordinating the work for CAD.

• Supervise the training/development of new trainee draftsperson and students

We are urgently seeking for interested candidates to undertake the following positions below for BRUNEI. These are Permanent. If you are interested, please send us your suitable UPDATED CV as per above descriptions with the requested documents/details per return.   
Bhuvan Kumar

Engineering Manpower Consultants (Oil & Gas)

Bhuvankumar Consulting, India

Mob: +91-9873720765, 9212575722

Please note: We do not charge any sort of fees whatsoever from the Candidates.

Sr. PDMS Piping Designer Aberdeen

Posted by Antony Thomas at Monday, November 21, 2011

Senior PDMS Piping Designer-Aberdeen

Job Title

Senior PDMS Piping Designer

Job Reference

Job Type
Contract/Temporary Positions



Apply by
25 November 2011

Job description
To carry out design activities within an area of a project and ensure that the technical and safety integrity of the design is maintained and that the Company and Project procedures are adhered to
To ensure that the work allocated is completed in compliance with Line Managers requirements
To ensure that the inter-discipline aspects of the design are addressed
To ensure the generation of project drawing deliverables is via AKMS (including “check-in” / check-out”, if applicable)
The maintenance of professional standards with regard to both attitude and work
Ensuring that Designers and CAD Operators are fully acquainted with the appropriate use of AKIMS.
To coach less experienced members within the squad to assist with their development
The preparation of drawings and or modelling related to discipline in accordance with the agreed workscope, man-hours and schedule
The carrying out of Single Discipline checking of Designers and CAD Operators work in accordance with the Company / Project procedures including PEM
The carrying out of Onshore or Offshore Site Surveys, as required, to assist in the initial workscope definition or the development of the design and the compilation of a survey report in accordance with the Company / Project procedures
Ensuring that the work is carried out in accordance with the requirements of the current releases of any Company / Client or Statutory Design Codes, Standards or Procedures
HNC or HND in a Relevant Engineering Discipline preferred
ONC (or Equivalent) in a Relevant Engineering Discipline preferred
Current Offshore Survival Certificate
Current Medical Certificate
Working knowledge of 2D CAD systems (AutoCAD / Microstation) preferred
Working Knowledge of PDMS (3D CAD system) preferred
Demonstrable experience within an engineering industry as a Designer/Senior Designer
Industry recognized training where applicable
Good team working
Good organizational
Pro-active attitude
Must be eligible to work within the UK

Apply On-line

Design Coordinator/Designer-Aker Singapore

Posted by Antony Thomas at

Design Coordinator/Designer 11-3165

Job Title
Design Coordinator/Designer

Job Reference

Job Type
Permanent Position (staff)




Apply by
30 November 2011

Job description

Aker Solutions ASA, through its subsidiaries and affiliates ("Aker Solutions"), is a leading global oil services company that provides engineering services, technologies, product solutions and field-life solutions for the oil and gas industry. The Aker Solutions group is organised in a number of separate legal entities. Aker Solutions is used as the common brand/trademark for most of these entities.

Aker Solutions' parent company is Aker Solutions ASA.  Aker Solutions has aggregated annual revenues of approximately NOK 35 billion and employs approximately 17 000 people in about 30 countries.

Job Summary

Create required concept, interface, design layout drawings and technical



1. Ensure all drawings produced are meet international drafting code and


2. Participate in designing of the proposed wellhead systems that meet

    customer tender requirements.

3. Create concept, interface, design layout drawing for the Tendering /

    Marketing group.

4. Perform basic mechanical engineering calculations.

5. Organize drawings and documents in accordance to engineering department



1. Diploma in Mechanical Engineering with at least 3 years experience in 

    a related field or

2. Nitec in Product Design or Higher Nitec in Mechanical Engineering with at least 5 years in a related field.

3. Fresh graduates are welcome to apply.


1. Proficient in the use of AutoCAD. Competency in the sue of the following

    software is a plus: Solidworks, SAP.

2. Able to communicate in English effectively.

3. Able to work independently with minimal supervision.

4. Hardworking with hands on approach towards work.

Work Place

Singapore Science Park

Apply On-line


Posted by Antony Thomas at Saturday, November 19, 2011


Job Title: MDS Specialist


Houston, TX

Start Date
30 Nov 2011

Job Description
Our client is currently recruiting for a highly motivated Multi Discipline Support (MDS) Specialist.
The wide spectrum of industry experience our client has means our projects will challenge your abilities to work in shallow to ultra-deep water depths with projects that include SPM systems, FPSOs, FSOs, MOPUs, TLPs, as well as drilling and production semi-submersibles. Our client’s research and development team is broadening this product line continually.
This position is a technical and lead role, responsible for supporting the MDS application, including troubleshooting, and the design of piping, electrical and instrument supports for all PDMS projects.
The successful candidate will possess strong organizational skills, along with good communication, leadership and interpersonal skills. Will be able to support MDS, including troubleshoot MDS problems and will train others as required. The MDS Specialist will lead a team of MDS designers supporting all ongoing projects.
Some College and 7 plus years of relevant Aveva 3D PDMS experience as a discipline specialist required.
The successful employee may be expected to travel on domestic and international assignments as needed.
Headquartered in West Houston, our client offers excellent benefits, tremendous opportunities for qualified professionals, and competitive salary and benefits packages.
If you are interested in this role, please contact Thomas Curran at Air Energi.
Tel: 281 983 8723

PDMS Support Specialist-Houston, TX

Posted by Antony Thomas at


Job Title

PDMS Support Specialist


Houston, TX

Start Date
30 Nov 2011

Job Description
Our client is currently recruiting for a highly motivated PDMS Piping Layout Specialist. The wide spectrum of industry experience our client has means our projects will challenge your abilities to work in shallow to ultra-deep water depths with projects that include SPM systems, FPSOs, FSOs, MOPUs, TLPs, as well as drilling and production semi-submersibles. Our client’s research and development team is broadening this product line continually.
Our client is currently recruiting for a Senior PDMS Piping Layout Designer. This Senior role will be responsible for overall Module, Topsides and Turret layouts for equipment and piping systems within a PDMS environment , to meet client and project requirements. The Senior PDMS Piping Layout Designer will conduct design reviews with project personnel including client representatives and also be responsible for designs from initial conceptual through to the fabrication & commissioning phase.
High school diploma or equivalent technical school certificate required. Associate Degree preferred.
10 years of experience in piping systems design including overall module plant layout of equipment required. 2 years of those as a project lead designer using PDMS required. Knowledge of equipment access, egress and maintenance required. FPSO,TLP, Semi-sub offshore and turret design experience preferred. Fabrication yard experience preferred.
Headquartered in West Houston, our client offers excellent benefits, tremendous opportunities for qualified professionals, and competitive salary and benefits packages.
The successful employee may be expected to travel on domestic and international assignments as needed.
If you are interested in this role, please contact Thomas Curran at Air Energi.
Tel: 281 983 8723


Tom Curran

Engineers, Designers Required For Overseas Positions

Posted by Antony Thomas at Thursday, November 17, 2011

KIRPALANEY & ASSOCIATES (ENGINEERS) PRIVATE LIMITED, a global leader in offering technical support services to all major oil, gas, chemical, petrochemical, power, offshore and other process plant industries,  is in need of highly qualified personnel for their clients Overseas on immediate basis

Managers / Discipline Heads
Project Managers / Engineers
Process Engineers
Lead Engineers / Engineers
Designers / Checkers
PDS / PDMS / Intool Designers & Engineers
Offshore Engineers - Design
Commission Engineers - Mechanical
For all positions the candidates should have min 5 years of experience. Excellent growth opportunities and overseas exposure.
On short listing you would be informed. It would then be mandatory that the candidate meet with us prior to us suggesting our overseas clients on your final selection. Preference would be given to candidates who meet with us at our office.
Please send in your CV ASAP

Kirpalaney & Associates (Engineers) Private Limited

Fleet Office, Delstar1st Floor
9-9A N S Patkar Marg, Kemps Corner
Mumbai 400 036

+91-22-23805558/9  +91-22-23806100


Posted by Antony Thomas at


The objective of the steam distribution system is to supply steam at the correct pressure to the point
of use. It follows; therefore, that pressure drop through the distribution system is an important feature.
One of the most important decisions in the design of a steam system is the selection of the
generating, distribution, and utilization pressures. Considering investment cost, energy efficiency, and
control stability, the pressure shall be held to the minimum values above atmospheric pressure that
are practical to accomplish the required heating task, unless detailed economic analysis indicates
advantages in higher pressure generation and distribution.
The piping system distributes the steam, returns the condensate, and removes air and noncondensable
gases. In steam heating systems, it is important that the piping system distribute steam,
not only at full design load, but also at partial loads and excess loads that can occur on system warmup.
When the system is warming up, the load on the steam mains and returns can exceed the
maximum operating load for the coldest design day, even in moderate weather. This load comes from
raising the temperature of the piping to the steam temperature and the building to the indoor design

Energy Considerations
Steam and condensate piping system have a great impact on energy usage. Proper sizing of system
components such as traps, control valves, and pipes has a tremendous effect on the efficiencies of
the system.
Condensate is a by-product of a steam system and must always be removed from the system as
soon as it accumulates, because steam moves rapidly in mains and supply piping, and if condensate
accumulates to the point where the steam can push a slug of it, serious damage can occur from the
resulting water hammer. Pipe insulation also has a tremendous effect on system energy efficiency. All
steam and condensate piping should be insulated. It may also be economically wise to save the
sensible heat of the condensate for boiler water make-up systems operational efficiency
Oversized pipe work means:
• Pipes, valves, fittings, etc. will be more expensive than necessary.
• Higher installation costs will be incurred, including support work, insulation, etc.
• For steam pipes a greater volume of condensate will be formed due to the greater heat loss.
This, in turn, means that either:
• More steam trapping is required, or wet steam is delivered to the point of use.
In a particular example:
• The cost of installing 80 mm steam pipe work was found to be 44% higher than the cost of 50
mm pipe work, which would have had adequate capacity.

The heat lost by the insulated pipe work was some 21% higher from the 80 mm pipeline than it
would have been from the 50 mm pipe work. Any non-insulated parts of the 80 mm pipe would
lose 50% more heat than the 50 mm pipe, due to the extra heat transfer surface area.
Undersized pipe work means:
• A lower pressure may only be available at the point of use. This may hinder equipment
performance due to only lower pressure steam being available.
• There is a risk of steam starvation.
• There is a greater risk of erosion, water hammer and noise due to the inherent increase in steam
The allowance for pipe fittings:
The length of travel from the boiler to the unit heater is known, but an allowance must be included
for the additional frictional resistance of the fittings. This is generally expressed in terms of
‘equivalent pipe length’. If the size of the pipe is known, the resistance of the fittings can be
calculated. As the pipe size is not yet known in this example, an addition to the equivalent length can
be used based on experience.
• If the pipe is less than 50 metres long, add an allowance for fittings of 5%.
• If the pipe is over 100 metres long and is a fairly straight run with few fittings, an allowance for
fittings of 10% would be made.
• A similar pipe length, but with more fittings, would increase the allowance towards 20%.
4.3 Selection of pipe size
There are numerous graphs, tables and slide rules available for relating steam pipe sizes to flow
rates and pressure drops.
To begin the process of determining required pipe size, it is usual to assume a velocity of flow. For
saturated steam from a boiler, 20 - 30 m/s is accepted general practice for short pipe runs. For major
lengths of distribution pipe work, pressure drop becomes the major consideration and velocities may
be slightly less. With dry steam, velocities of 40 metres/sec can be contemplated -but remember that
many steam meters suffer wear and tear under such conditions. There is also a risk of noise from
Draw a horizontal line from the saturation temperature line (Point A) on the pressure scale to the
steam mass flow rate (Point B).
• From point B, draw a vertical line to the steam velocity of 25 m/s (Point C). From point C, draw a
horizontal line across the pipe diameter scale (Point D).

The following table also summaries the recommended pipe sizes for steam at various pressure and
mass flow rate.

Piping Installation
1. All underground steam systems shall be installed a minimum of 10 feet from plastic piping and
chilled water systems. All plastic underground piping must be kept at a 10 foot distance from
steam/condensate lines.
2. Install piping free of sags or bends and with ample space between piping to permit proper
insulation applications.
3. Install steam supply piping at a minimum, uniform grade of 1/4 inch in 10 feet downward in the
direction of flow.
4. Install condensate return piping sloped downward in the direction of steam supply. Provide
condensate return pump at the building to discharge condensate back to the Campus collection
5. Install drip legs at intervals not exceeding 200 feet where pipe is pitched down in the direction
of the steam flow. Size drip legs at vertical risers full size and extend beyond the rise. Size drip
legs at other locations same diameter as the main. Provide an 18-inch drip leg for steam mains
smaller than 6 inches. In steam mains 6 inches and larger, provide drip legs sized 2 pipe sizes
smaller than the main, but not less than 4 inches.
6. Drip legs, dirt pockets, and strainer blow downs shall be equipped with gate valves to allow
removal of dirt and scale.
7. Install steam traps close to drip legs.



Minimum Access Provisions-Process Unit and Offsites

Posted by Antony Thomas at Wednesday, November 16, 2011

Minimum Access Provisions-Process Unit and Offsites Layout


Type of
Item to be Accessed

- Items Located
Over Platform

heat exchangers
control valves (all sizes)
(higher than 3658 mm (12 ft.) above grade)
valves (NPS 102 mm (4”) inlet and larger on vertical vessel)
blinds (higher than 3658 mm (12 ft.) above grade)
soot blowers
burners (when not accessible from grade)
observation doors and sample ports (higher than 3658 mm
ft.) above grade)
Elevated cleanouts

- Items Located
at Edge of Platform

102 mm (4”) and larger gate and globe valves at vessels
limit valves in elevated pipe racks
motor operated valves
valves - NPS 77 mm (3”) inlet and smaller on vertical vessels
valves - All sizes on horizontal vessels
controllers (higher than 3658 mm (12 ft.) above grade)
devices on vessels (higher than 3658 mm (12 ft.) above

Permanent Ladder

sizes of check valves at vessels
77 mm (3”) and smaller gate and globe valves at vessels
controllers between 2134-3658 mm (7-12 ft.) above grade
gauges and valves
observation ports between 2134-3658 mm (7-12 ft.) above grade
requiring routine access
Elevated electrical
substations and equipment

Mobile Stair

servicing between 2134-3658 mm (7-12 ft.) above grade except as
noted in this Table

No Permanent Access

valves in pipe racks (except at battery limit)
orifices or meter runs
on vessels (without process blinds or valves)
valves not at vessels
connections in piping
connections in piping
or exhaust heads
temperature measuring points on vessels
connections on furnaces

Hydrocarbon Processing’s Refining Processes Handbooks

Posted by Antony Thomas at Tuesday, November 15, 2011


Hydrocarbon Processing’s Refining Processes Handbooks

reflect the dynamic advancements now available in licensed process
technologies, catalysts and equipment. The global refining industry is
under tremendous pressure to process “cleaner” transportation fuels
with varying specifications for a global market. Refiners must balance
capital investment and operating strategies that provide the optimum
pro. stability for their organization. Hence, global refining organizations
will apply leading-edge technology in conjunction with “best practices’
for refining fuels and petrochemical feedstocks from crude oil.
HP’s Process handbooks are inclusive catalogs of established and
emerging refining technologies that can be applied to existing and
grassroots facilities. Economic stresses drive efforts to conserve energy
consumption, minimize waste, improve product qualities, and, most
important, increase yields and throughput.
In further expansion, the process entries presented an expanded
description of the licensed technology including a process .Now
diagram, product description, economic information and other vital
information. Specific processing operations to be emphasized
include alkylation, coking, (crude) distillation, catalytic cracking (fluid
and resid), hydrocracking, hydrotreating, hydrogen, isomerization,
desulfurization, lube treating, visbreaking, etc.


What is the major difference between PDS course & PDMS course regarding Pipe Designing?

Posted by Antony Thomas at

What is the major difference between PDS course & PDMS course regarding Pipe Designing?

PDS :-Plant Design System

PDMS :- Plant Design Management System


There are major differences between PDMS and PDS.


First of all the database structure is totally different. PDS is a lot less user friendly, much more labor intensive than PDMS


But you're asking about Piping Design specifically.


Visually PDMS is way better. You can rotate through a rendered model while designing.

In PDS you mainly see lines. and top views north view etc. rotating is possible, but you'll get lost and if the model is crowded you better dont cuz the view will take ages to refresh.

In PDS you'll get lost when working in crowded areas, and need smart plant review to see what you've actually done.PDS clash check is a disaster.

in PDMS you immediately see what you do, you can rotate around your work to see if it's done right without clashing, clash checking utility is way more user friendly.


in PDMS you can customize everything.

also your own commands in form and buttons.


in PDS you are bound to buttons provided by Intergraph



Again PDS is much more labor intensive. If you need to reroute/modify a line in PDS deleting and starting over would be the fastest way. In PDMS you can move/rotate each component to what ever direction you want, and you're not bound to that ridiculous segment line.



I could go on for ages to name points in which PDMS is proffered over PDS.


Last but not least, PDS is dying; Intergraph is not supporting it any more.


If you have to make a decision which system to use, I recommend PDMS by far.


And most probably everyone who knows both prefers PDMS by far. I talk from my own experience and opinions of a lot of people I met in the business.

(Except the ones owning Intergraph stocks... poor critters)


Have a look at\pdms


Ref: Yahoo/answers

PDS as you know uses Oracle so it has a very powerful database, the major difference between them is about PDS is american and PDMS is a british software so to be honest, it is matter of your client and environment which will tell you which software you should use, if they are using PDS you'd better use PDS, none of them are Autocad base, Autoplant from former Rebis and Cadpipe from COADE are cad base but PDMS and PDS are not cad base and you know PDS needs microstation. 


Posted by Antony Thomas at Monday, November 14, 2011





The purpose of the compressed air piping system is to deliver compressed air to the points of usage.

The compressed air needs to be delivered with enough volume, appropriate quality, and pressure to properly power the components that use the compressed air. Compressed air is costly to manufacture. A poorly designed compressed air system can increase energy costs, promote equipment failure, reduce production efficiencies, and increase maintenance requirements. It is generally considered true that any additional costs spent improving the compressed air piping system will pay for them many times over the life of the system.

compressed air

Piping materials


Common piping materials used in a compressed air system include copper, aluminum, stainless steel and carbon steel. Compressed air piping systems that are 2" or smaller utilize copper, aluminum or stainless steel. Pipe and fitting connections are typically threaded. Piping systems that are 4" or larger utilize carbon or stainless steel with flanged pipe and fittings. Plastic piping may be used on compressed air systems; however caution must used since many plastic materials are not compatible with all compressor lubricants. Ultraviolet light (sun light) may also reduce the useful service life of some plastic materials. Installation must follow the manufacturer's instructions. Corrosion-resistant piping should be used with any compressed air piping system using oil-free compressors. A non-lubricated system will experience corrosion from the moisture in the warm air, contaminating products and control systems, if this type of piping is not used. It is always better to oversize the compressed air piping system you choose to install. This reduces pressure drop, which will pay for itself, and it allows for expansion of the system.


Compressor Discharge Piping


The discharge piping from the compressor should be at least as large as compressor discharge connection and it should run directly to the after cooler. Discharge piping from a compressor without an integral after cooler can have very high temperatures. The pipe that is installed here must be able to handle these temperatures. The high temperatures can also cause thermal expansion of the pipe, which can add stress to the pipe. Check the compressor manufacturer's recommendations on discharge piping. Install a liquid filled pressure gauge, a thermometer, and a thermo well in the discharge airline before the after cooler. Proper support and/or flexible discharge pipe can eliminate strain.


1. The main header pipe in the system should be sloped downward in the direction of the compressed air flow. A general rule of thumb is 1" per 10 feet of pipe. The reason for the slope is to direct the condensation to a low point in the compressed air piping system where it can be collected and removed.


2. Make sure that the piping following the after cooler slopes downward into the bottom connection of the air receiver. This helps with the condensate drainage, as well as if the water-cooled after cooler develops a water leak internally. It would drain toward the receiver and not the compressor.


3. Normally, the velocity of compressed air should not be allowed to exceed 6 m/s; lower velocities are recommended for long lines. Higher air velocities (up to 20 m/s) are acceptable where the distribution pipe-work does not exceed 8 meters in length. This would be the case where dedicated compressors are installed near to an associated large end user.


4. The air distribution should be designed with liberal pipe sizes so that the frictional pressure losses are very low; larger pipe sizes also help in facilitating system expansion at a later stage without changing header sizes or laying parallel headers.


Pressure Drop


Pressure drop in a compressed air system is a critical factor. Pressure drop is caused by friction of the compressed air flowing against the inside of the pipe and through valves, tees, elbows and other components that make up a complete compressed air piping system. Pressure drop can be affected by pipe size, type of pipes used, the number and type of valves, couplings, and bends in the system. Each header or main should be furnished with outlets as close as possible to the point of application. This avoids significant pressure drops through the hose and allows shorter hose lengths to be used. To avoid carryover of condensed moisture to tools, outlets should be taken from the top of the pipeline. Larger pipe sizes, shorter pipe and hose lengths, smooth wall pipe, long radius swept tees, and long radius elbows all help reduce pressure drop within a compressed air piping system.

The discharge pressure of the compressor is determined by the maximum pressure loss plus operating pressure value so that air is delivered at right pressure to the farthest equipment. For example, a 90 psig air grinder installed in the farthest drop from the compressor may require 92 psig in the branch line 93 psig in the sub-header and 94 psig at the main header. With a 6 psi drop in the filter/dryer, the discharge pressure at the after cooler should be 100 psig.

Piping system Design

There are two basic systems for distribution system.
1. A single line from the supply to the point(s) of usage, also known as radial system
2. Ring main system, where supply to the end use is taken from a closed loop header. The loop
design allows airflow in two directions to a point of use. This can cut the overall pipe length to
a point in half that reduces pressure drop. It also means that a large volume user of
compressed air in a system may not starve users downstream since they can draw air from
another direction. In many cases a balance line is also recommended which provides another
source of air. Reducing the velocity of the airflow through the compressed air piping system is
another benefit of the loop design. This reduces the velocity, which reduces the friction
against the pipe walls and reduces pressure drop.

Compressed Air leakage

Leaks can be a significant source of wasted energy in an industrial compressed air system and may
be costing you much more than you think. Audits typically find that leaks can be responsible for
between 20-50% of a compressor’s output making them the largest single waste of energy. In
addition to being a source of wasted energy, leaks can also contribute to other operating losses:
• Leaks cause a drop in system pressure. This can decrease the efficiency of air tools
and adversely affect production
• Leaks can force the equipment to cycle more frequently, shortening the life of almost all
system equipment (including the compressor package itself)
• Leaks can increase running time that can lead to additional maintenance requirements
and increased unscheduled downtime
• Leaks can lead to adding unnecessary compressor capacity
Observing the average compressor loading and unloading time, when there is no legitimate use of
compressed air on the shop floor, can estimate the leakage level. In continuous process plants, this test
can be conducted during the shutdown or during unexpected production stoppages.
Air Leakage =                           On load time
                                     Q x --------------------------------------
                                               On load time + Off load time

Where Q = compressor capacity

Leakage reduction

Leakage tests can be conducted easily, but identifying leakage points and plugging them is laborious
work; obvious leakage points can be identified from audible sound; for small leakage, ultrasonic
leakage detectors can be used; soap solution can also be used to detect small leakage in accessible
When looking for leaks you should investigate the following:
CONDENSATE TRAPS -Check if automatic traps are operating correctly and avoid bypassing.
PIPE WORK - Ageing or corroded pipe work.
FITTINGS AND FLANGES - Check joints and supports are adequate. Check for twisting.
MANIFOLDS - Check for worn connectors and poorly jointed pipe work.
FLEXIBLE HOSES - Check that the hose is moving freely and clear of abrasive surfaces. Check for
deterioration and that the hose has a suitable coating for the environment e.g. oily conditions. Is the
hose damaged due to being too long or too short?
INSTRUMENTATION - Check connections to pneumatic instruments such as regulators, lubricators,
valve blocks and sensors. Check for worn diaphragms.
PNEUMATIC CYLINDERS Check for worn internal air seals.
FILTERS Check drainage points and contaminated bowls.
TOOLS Check hose connections and speed control valve. Check air tools are always switched off
when not in use.
The following points can help reduce compressed air leakage:
• Reduce the line pressure to the minimum acceptable; this can be done by reducing the discharge
pressure settings or by use of pressure regulators on major branch lines.
• Selection of good quality pipe fittings.
• Provide welded joints in place of threaded joints.
• Sealing of unused branch lines or tapings.
• Provide ball valves (for isolation) at the main branches at accessible points, so that these can be
closed when air is not required in the entire section. Similarly, ball valves may be provided at all end
use points for firm closure when pneumatic equipment is not in use.
• Install flow meters on major lines; abnormal increase in airflow may be an indicator of increased
leakage or wastage.
• Avoid installation of underground pipelines; pipelines should be overhead or in trenches (which can
be opened for inspection). Corroded underground lines can be a major source of leakage.

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