What schedule is gas pipe?

As the department of Petroleum resources cracks down on illegal Liquified Petroleum Gas(cooking gas) stations and poorly installed LPG facilities nationwide, it is important to know some key information around LPG installation and the plumbing of the lines using steel pipes.

To take LPG (cooking gas) from the storage tank and dispense into cylinders, an installer will have to connect the tank through the pumps, compressors to the dispensing units with steel pipes.. For this piece we will discuss the various schedules of steel pipes and their applications when it comes to the installation of LPG (cooking gas) plants in Nigeria.
 

WHAT IS THE MEANING OF THE TERM SCHEDULE?
“Schedule” is the standard of wall thickness that has been adopted by the American National Standards Institute. As per the Institute, the thickness of wall pipes varies from Schedule 10, Schedule 40, Schedule 80, and Schedule 160.

WHAT IS STEEL PIPE DIMENSIONS SCHEDULE?

Steel pipe schedule is an indicating method represented by ASME B 36.10, and also used in many other standards, marked with “Sch”. Sch is the abbreviation of schedule, generally appearing in the American steel pipe standard, which is a prefix of a series number. For example, Sch 80, 80 is a pipe number from chart/table ASME B 36.10.

THE PIPE SCHEDULE FORMULA:

Sch.=P/[ó]t×1000

P is the Designed pressure, units in MPa;

[ó]t is Allowable stress of materials under design temperature, Units in MPa.

WHAT DOES SCH MEAN FOR THE STEEL PIPE DIMENSIONS

As describing the steel pipe parameter, we usually use the pipe schedule, it is a method that represent pipe wall thickness with number. Pipe schedule (sch.) is not a wall thickness, but a wall thickness series. Different pipe schedule means different wall thickness for the steel pipe in the same diameter. The most frequently indications of schedule are SCH 5, 5S, 10, 10S, 20, 20S, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160. The larger the table number, the thicker the surface pipe wall, the higher the pressure resistance.

For the purpose of this piece we will narrow down our comparison to Schedule 40 and 80 pipes as they are the most widely used for LPG and Gas Installations in Nigeria.

DIFFERENCE BETWEEN SCHEDULE 40 AND 80 PIPES?

There are several differences in the application, cost of the pipes, we would discuss in details below

1. APPLICATION

“Schedule 40” and “Schedule 80” refer to the thickness of the walls of pipes. Pipes with Schedule 40 come with standard weight, and pipes with schedule 80 come with extra strength. The materials used for making Schedule 40 and Schedule 80 come from the same material.

Schedule 80 pipes have a thicker wall than Schedule 40 pipes. As such, Schedule 80 pipes are stronger than Schedule 40 pipes. Though both pipes are used in Gas construction and Installation work, Schedule 40 is used more often. Schedule is used more often in Nigeria at the Retail plants because of low pressure.

At the midstream level where the pressure is higher and a stronger pipe is needed, then the engineers would go for Schedule 80 pipes. Schedule 80 pipes are used where the pipes have to be exposed. But if there is no need for any extra strength, Schedule 40 pipes are sufficient.

2. COST

The cost of Schedule 40 and Schedule 80 pipes are different because of the difference in the quantity of materials. As Schedule 80 pipes consist of more materials, the price is considerably higher than Schedule 40 pipes. Schedule 80 pipes are also more costly as the cost of production is greater. To get a better understanding of the local retail price in Nigeria, a 2 Inches one length (5.8metres) of schedule 40 pipes is NGN40,000 ($111) while the cost of a 2 Inches one length (5.8metres) of schedule 80 pipes is NGN62,500 ($174).

3. WORKING AND BURSTING PRESSURE

The bursting pressures are based on Barlow's formula. The working pressures are based on factor 8.

Dimensions according ASME/ANSI B36.10/19.
 

THE WORKING AND BURSTING PRESSURE FOR SCHEDULE 40 PIPES

 

THE WORKING AND BURSTING PRESSURE FOR SCHEDULE 80 PIPES

SUMMARY:

• Pipes with Schedule 40 come with a standard weight, and pipes with Schedule 80 come with extra strength.
• Schedule 80 pipes are stronger than Schedule 40 pipes.
• Though both pipes are used in Gas and LPG construction and Installation work, Schedule 40 is used more often.
• Schedule 80 pipes are used where the pressure is very high. But for retail LPG installations,
  40 pipes are sufficient.
• When comparing the weight, Schedule 40 pipes come in less weight than Schedule 80 pipes.
• As Schedule 80 pipes consist of more materials, the price is considerably higher than Schedule 40 pipes.

If you need to discuss any related steel and Gas Business development write us at gaspreneur@kiakiagas.com or call/whatsapp on +2348085269320

 

Sources:
https://www.engineeringtoolbox.com/wrought-steel-pipe-bursting-pressure-d_1123.html

http://www.abtersteel.com/news/products-news/difference-between-sch-40-and-sch-80-steel-pipe/

Image Credits:

https://www.engineeringtoolbox.com/wrought-steel-pipe-bursting-pressure-d_1123.html
https://tpf.eu/projects/lpg-bottling-plant-arzew/

 

 

If you are new to the world of in-situ machining one of the essential things you must learn is how pipe sizing works.

There’s not a huge amount to remember, but you do need to familiarize yourself with the terminology and the underlying methods behind how pipes are classified by manufacturers in the oil and gas sector.

What is the NPS of a pipe?

So what exactly does NPS mean? Is it the inside diameter, the outside diameter? or the wall thickness?

The answer is none of the above.

‘NPS’ is an abbreviation of Nominal Pipe Size, which is a term used as a guideline number defining the diameter of the pipe.

What is pipe NB (Nominal Bore)?

This is just the same as NPS. ( It is a common way of describing pipe sizes used in the USA).

What is DN (Diameter Nominal)?

This is the international and European metric method used to describe NPS (or NB).

DN pipe sizes numbers are therefore different to NPS.  For example the metric equivalent of an NPS 6 pipe (6”) is DN 150. (To convert from NPS 6 to DIN simply multiply the 6 x 25=150. (150mm)

What is a Pipe Schedule?

Pipe schedule (SCH) is how the wall thickness of a pipe is described. It is not an actual measurement,  but a guide number based on a wall thickness formula.

Two pipes the same diameter may have different schedules, which means they have a different wall thickness. So somebody specifying a pipe for a high pressure application will select a bigger number which represents a bigger schedule (wall thickness).

Additionally, in the case of stainless steel,  piping schedules are specified with a letter ‘s’ as a suffix after the number. An example to illustrate is an NPS 14 pipe with a schedule of 40s shown in the table below.

The reason stainless steel is schedules are treated in this way is due to their extra strength. Less wall thickness is required to withstand the same pressure as compared with other steels.

NPS Nominal Pipe Size   40 Schedule40s Schedule140.438″ wall thickness0.375″ wall thickness

The list of pipe schedules used today are as follows; 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, STD, XS AND XXS.

Just when you thought you were beginning to understand pipe sizing unfortunately there’s an added complexity to be aware of:

Different sizes of pipes are manufactured in different ways and this has affected how pipe sizing works.

What this means is that sizes (NPS) ⅛″ up to 12″ have an outside diameter that is greater than its nominal pipe size, whereas pipe sizes 14″ and above have an outside diameter equal to its nominal pipe size. The diagram below illustrates the point.

Pipe Sizing Charts

If you Google ‘Pipe Size Charts’, you’ll find plenty of pipe manufacturers who offer these to download from their website. We’ve also created our own for you to download Pdf documents using the links below. Depending on your location choose  between inches or mm and download for free.

Download NPS (Inches) Pipe Size Chart – (US Letter Size Pdf)

Download DN (mm) Pipe Size Chart – (A4 Size Pdf)

What equipment is available to machine pipe?

If you are looking to cut, bevel, or tap into metal pipes there is a wide range of portable machine tools available.

Pipe Cutting and Beveling

For cutting and bevelling pipelines at on-site at locations such as offshore platforms, petrochemical plant and power stations the tried and test solution is to use a clamshell cutter (also known as a split from cutter). These are available in many sizes with some even capable of machining diameters as large as 180”!

Hot Tapping

When maintenance work on an active pipeline is needed a hot tapping machine can be used. This could be to repair a section of pipeline, or when a new branch needs to be added. The benefit of a hot tapping machine is that the work can be carried out without major disruption to the flow of product through the pipeline.

Milling Pipe Seam Welds

On occasions where subsea pipe connectors are to be used for attaching a new pipe run, it may be necessary to remove seam welds from the pipe to ensure a good fit. This operation is carried out using a portable milling rail attached to the pipe with a chain clamp.

Decommissioning Pipelines

For decommissioning pipelines, a subsea diamond wire saw can be used. These can be either lowered from deck above the surface or hooked up to a remotely operated vehicle (ROV).

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