MOVING FLUIDS THROUGH PIPING, TUBING, and HOSES

Wild Thing, I think you move me
But I wanna know for sure
So, come on, and hold me tight
You move me

("Wild Thing," by The Wild Ones but made famous by The Troggs, 1966)

THE PTOA PIPING NETWORK HARDWARE FOCUS STUDY BEGINS

Piping Networks ... and the Vessels and Reactors they incorporate into their networks ... make continuous processing possible. Feedstocks and Intermediate Products continuously flow through these members of the Stationary Equipment family. Unlike members of the Rotating Equipment family, there are no moving parts in Stationary Equipment.

The purpose of a Piping Network is to move fluids from one place in the processing facility to another place in the processing facility. No Piping Network, no PV Flowrate!

Guess what?

The Reaction Furnace Tubes used to convert natural gas into hydrogen must be made from Titanium.

The selection of Piping hardware used for each Process Line, Utility/Service Line, Pipe Fitting, and Valve is not random.

Relying on any ole pipe lying around to do the job of moving fluids is a guaranteed safety and maintenance nightmare for the processing facility.

Pipe Pressure Rating Charts take practice to interpret. This is a Burst Pressure Chart for PVC Piping. Schedule 80 PVC Pipe has a thicker wall than Schedule 40 Pipe and can withstand more flowing fluid Pressure.

The Engineering and Construction (E&C) company selected to design the process facility specifies each piece of Stationary Equipment based upon the fluid's flowing characteristics, flowing PV Temperature, flowing PV Pressure, and the amount of fluid that needs to be delivered over a range of throughput.

Each Pipe and piece of Stationary Equipment is designed to withstand the greatest Pressure energy that the fluid might encounter which typically does not occur during normal operating conditions. Pressure Ratings for Piping will be featured in an upcoming PTOA Segment.

Once the materials of manufacture and the Pressure Rating for each flowing fluid has been determined, the optimal size pipe will be selected.

Selection of the pipe size likewise determines the Volumetric Flowrate.

The Inside Diameter of the pipe impacts the PV Flowrate AND the amount of Pressure Drop through the segment of Piping. The smaller the ID, the greater the Pressure drop through the same length of pipe, and vice versa.

Every PTOA Reader and Student learned in PTOA Segment #235 that the Volumetric Flowrate is determined by two factors, the fluid's Velocity (V) and the Cross-Sectional Area of the Pipe that the fluid is flowing through (A).

Furthermore, the E&C company will design the facility to minimize the Pressure Drop losses caused by the friction between the flowing fluid and the interior wall of the pipe that the fluid is flowing through. Flowing fluid friction losses were feature in PTOA Segment #165.

FLUID CONVEYANCE HARDWARE: PIPING, TUBING, and HOSES

This Process Facility is constructed with Pipe and Pipe Fittings and a variety of Valves that are sized to match each Process Stream's Pressure Rating.

The conveyance of fluids from one point to another is done by the following types of hardware:

Piping
Tubing
Hoses

The difference between Piping and Tubing is nuanced, which means the answer given depends upon the source that is asked.

Some sources will state that the smallest Pipe Diameter is 1/4^th inch and below that diameter Tubing is the option; however, other sources will list Pipe Diameters smaller than 1/4^th inch.

This Pilot Plant transports fluids via Tubing. "Scale Up" to a commercial size plant pends promising results from the Pilot Plant.

Generally speaking, Piping is used in large industrial applications and Tubing is used in smaller process applications wherein the smaller diameter Tubing will adequately deliver the amount of fluid that needs to be transported.

For example, Piping would be used to construct all the processing facilities that have been pictured in the PTOA. However, Tubing was used in the pilot plant which was built to research whether or not the process should be "scaled up" to commercial production level.

The Conduit that protects automatic instrumentation signal formats is made from Tubing.

Metal Tubing is carefully bent into conduits through which automatic signal transmission wires are protected. Tubing is also used to deliver instrument Air to Automatic (Pneumatic) Control Valves. Tubing is also used to deliver important auxiliary fluids to Rotating Equipment.

Here are Piping Facts that may help distinguish Piping from Tubing:

Piping is used for transporting a large capacity of fluids.
The amount of fluid transferred is the primary criterion for Piping and the amount of flowing fluid needs to be predictable. For these reasons, Piping is rigid and always round in shape. A change in the direction of flow requires connecting the Tubing to a Fitting.
Piping is ordered using the Nominal Pipe Size Standard (NPS); The Nominal Diameter and the pipe wall thickness (aka Schedule Number) are stated. NPS and Pipe Schedules will be featured in the next PTOA Segment.

Here are Tubing Facts that may help distinguishing Tubing from Piping:

Tubing can be used in a variety of services which include the transport of fluids. Tubing may be round, square, or rectangular depending on its service.

Tubing can be carefully bent. Pipe is rigid so flow direction is changed by Pipe Fittings. Pipe Fittings have the potential to leak. Tubing has less leak potential.

Tubing is not as rigid as Pipe; some types of metal Tubing can be carefully bent to change the direction of flow without damaging the Tubing. For this reason, Tubing has potentially less leaks than Piping. Tubing can even be manufactured to "telescope" providing a sleeve over or expand into another section of Tubing.

Pipe is specified by Inner Diameter and Schedule. Tubing is specified by Outer Diameter and Wall Thickness.

Tubing is ordered to a precise Outer Diameter. The Wall Thickness is then specified. The Inner Diameter is determined by subtracting twice the Wall Thickness from the Outer Diameter.

High Pressure Hoses on a Gas Turbine. Note Tubing in lower right foreground.

Hoses are easy to distinguish from Piping and Tubing because they are built to be flexible and not rigid.

On the plus side, being flexible means that Hoses are less susceptible to vibration damage.

The trade-off for the flexibility is endurance; Hoses will not last as long as Tubing because Hoses are intentionally placed in services that expose them to daily wear and tear caused by friction and heat.

Oil-Resistant Steam Hose cutaway.

Hoses are typically manufactured from rubber and reinforced with wires or braids or even metal mesh for high Pressure service. The construction of Hoses makes them less subject to corrosion from transporting acids and corrosive substances. Hoses have Pressure Ratings that must not be exceeded.

PROCESS LINES AND UTILITY/SERVICE LINES

There are two main service classifications for the Piping and Tubing used in the construction of a processing plant.

(Major) Process Lines

A hot fluid exchanges its heat into a colder fluid in this set of Shell and Tube Heat Exchangers. The thick, black Process Lines to and from these Exchangers indicate these Process Streams are directly involved with the conversion of Feedstocks into Final Products. Note the thin black lines that connect the Process Lines to thermowells and drain/purging valves. The access to line purging is important during Turnaround but not needed during normal operations of the process unit.

Any fluid that is directly involved with the movement and delivery of Feedstocks, Intermediate Products, or Final Products is a (Major) Process Line.

As was mentioned way back in PTOA Segment #14, a Process Line is drawn as a thick black line on a Piping and Instrumentation Diagram (P&ID).

Otherwise stated, a thick black line drawn on a P&ID does not mean that line is a large diameter Pipe in the Real World; the thick black line only means the fluid flowing through that piece of Piping or Tubing is a Feedstock, or Intermediate Product, or Final Product.

Utility Lines/Service Lines aka Minor Process Lines

Major Process Lines are drawn as a thick black line on a P&ID. Utility Lines/Service LInes (aka Minor Process Lines) are drawn as thin black lines.

A Utility Line/Service Line indicates that the fluid flowing through the Piping or Tubing supports the processing of Feedstocks and Intermediate Products into Final Products.

A Utility Line/Service Line is drawn on a P&ID as a more-lightly-drawn and thinner black line. The thin black line could also indicate a connection to the (Main) Process Line, for example for a drain or thermowell.

So, Fred!

While you are decoding a P&ID and notice a thick black line which you know represents flowing Steam, that line could be the Steam Feedstock to a Reaction Furnace that converts natural gas to the desired hydrogen gas.

However a thinner black line that is also transporting Steam might be Steam used for heat transfer in a Reboiler.

Got it?

TAKE HOME MESSAGES: Stationary Hardware called Piping, Tubing, and Hoses transport fluids from one point in the continuously flowing process to another point in the continuously flowing process. Without Piping, Tubing, or Hoses the PV Flowrate would make no sense.

There are two types of fluid-flow services performed by Piping, Tubing, and Hoses:

Process Lines move Feedstocks, Intermediate Products, and Final Products to where they are next needed.
Utility Lines/Service Lines move fluids that are needed to support the conversion of Feedstocks and Intermediate Products into Final Products.
Utility Lines/Service Lines also connect hardware to the Process Lines.

Process Lines are drawn as thick, black lines on a P&ID. Utility/Service Lines are drawn as thinner black lines on a P&ID.

The selection of Piping, Tubing, and Hoses is not random; the E&C company that won the bid to design the processing facility takes each of the following items into account to size the fluid conveyance hardware:

The capacity range (aka range of PV Flowrate) needed to deliver the fluid to where it is needed.
The physical and chemical properties of the flowing fluid which is impacted by ...
The PV Pressure of the Flowing Gas Fluid and ...
The PV Temperature of the Flowing Gas or Liquid Fluid.

The above criteria are used to size the Piping, Tubing, or Hoses and determine the Pressure Rating of each Process or Service Line. The Pressure Ratings for Piping, Tubing, and Hoses must not be exceeded.

Piping is used for higher capacity PV Flowrates; Tubing is used for lower capacity PV Flowrates.

Piping is always used for moving and delivering fluids. Tubing is used for moving fluids and also used for other services ... like used as a protective covering (aka conduit).

Piping is always round and straight; a change in direction of flow requires connecting a Pipe Fitting. Tubing can be carefully bent to change the direction of the flowing fluid. Because Tubing has less Pipe Fittings, the potential for leaking is less in Tubing.

Piping is ordered by NPS; the Inner Diameter of the Pipe and Schedule (wall thickness) are specified. Tubing is ordered by the Outer Diameter and Wall Thickness (wt).

Unlike Piping or Tubing, Hoses are flexible. The flexibility of Hoses makes them able to withstand vibration better than Piping or Tubing. Hoses that can tolerate high pressure support Rotating Equipment ... like Gas Turbines.

The flexibility of Hoses subjects them to wear. Hoses must be checked for wear and tear on a regular basis.

PTOA PV FLOWRATE FOCUS STUDY AREA
PIPING NETWORK HARDWARE

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