BOBTAIL DELIVERY OPERATIONS MODULE 3 Bobtail Equipment and Systems 1

BOBTAIL DELIVERY OPERATIONS

MODULE 3

Bobtail Equipment and Systems

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LESSON 1


Introduction

To safely load bobtails at a bulk plant, you must understand the plant’s layout, equipment, and operating procedures. You must also monitor the operation and condition of all systems throughout the loading operation. The most common type of loading equipment used at a bulk plant is the plant pump. This module presents detailed procedures for loading a bobtail using the plant pump.

Objectives

After completing this module, you will be able to:

Identify differences in bulk plant designs and transfer operations List common bulk plant loading systems and equipment Identify steps for loading a bobtail using a plant pump Identify the purpose and function of vapor compressors and bobtail pumps

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LESSON 1

Bulk Plant Loading Systems and Equipment

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LESSON 1


Bulk Plant Design Variations

Bulk plant designs vary depending on:

Types of transfer operations conducted, such as railcar, cargo tanks, cylinder filling, recreational vehicle and motor fuel dispensing, and pipeline system supply

Number of bulk storage tanks Type and location of bulk storage tank valves

and fittings Equipment used to transfer liquid product to and

from storage and cargo tanks Piping layout Type and location of transfer bulkheads Type and location of operating controls and

emergency equipment Company operating procedures that apply to

loading

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LESSON 1


Single and Multiple Tank Bulk Plants

Single Tank Design

The simplest bulk plant design is a single bulk storage tank installation. Single tank bulk plants have a liquid loading pump and either:

One transfer bulkhead used for both unloading transports and loading bobtails, OR

Two transfer bulkheads where one is dedicated for unloading transports and the other for loading bobtails

Piping, valves, fittings, and transfer equipment for single tank bulk plants are generally uncomplicated and easy to identify and product flow is usually easy to trace and visualize.

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LESSON 1


Single and Multiple Tank Bulk Plants cont.

Multiple Tank Design

Multiple tank bulk plants require more complex piping systems, specialized valves, and controls. You must know and understand these more complex systems to perform your job safely.

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LESSON 1


Understanding Bulk Plant Transfer Operations

One way to become familiar with the transfer operations at a bulk plant is to trace the flow of propane liquid and vapor from the supply tank, through the piping systems, to the cargo tank. This process can be confusing at first especially in multiple tank bulk plants. Here are some things you can do that will help you understand this process:

Try to obtain a piping diagram of the plant and become familiar with piping labels or color coding.

Read any written plant operating procedures. Become familiar with the flow controls and

any other transfer operations in progress in other plant areas.

Talk to the plant manager, your supervisor, or other drivers about the bulk plant layout.

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Note: It is particularly important to understand transfer operations when loading a bobtail at a bulk plant for the first time or after significant modifications have been performed at a familiar plant.

LESSON 1


Liquid Transfer Pumps and Vapor Compressors

There are two main types of equipment used to transfer propane from the bulk plant storage tank to the bobtail cargo tank are:

Liquid transfer pumps: Also known as plant pumps, liquid transfer pumps transfer liquid propane directly from the storage tank, through the pump, and into the bobtail cargo tank. These pumps are designed to handle liquid propane.

Vapor compressors: Pull vapor from the bobtail cargo tank, compress it slightly, and then discharge it into the vapor space of the bulk storage tank. This causes the pressure in the storage tank to increase and the pressure in the bobtail to decrease, allowing liquid propane to flow from the storage tank into the bobtail cargo tank. Compressors are designed to only handle vapor and will be damaged if liquid propane is supplied to them.

Note: It is important to understand that excessive pressure in piping and containers can cause product discharge through a relief valve.

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LESSON 1


Liquid Transfer Pumps and Vapor Compressors cont.

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Vapor Compressor

Liquid Transfer Pump

LESSON 1


Transfer Hoses

During loading operations, you will use a plant liquid hose and a vapor equalizing hose to transfer propane from the storage tank to the bobtail:

Plant liquid hose: Moves liquid propane from the plant pump into the bobtail cargo tank.

Vapor equalizing hose: Carries vapor from the cargo tank back into the storage tank. As liquid propane moves from the storage tank into the bobtail cargo tank, the vapor equalizing hose helps to equalize pressure between the two tanks throughout the loading operation, which reduces wear and tear on the pump and decreases loading time.

Before loading your bobtail, always examine the condition of the bulk plant transfer hoses including hose couplings, clamps, fittings, and connections at the bulkhead.

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LESSON 1


Emergency Shutdown Systems

Every bulk plant is required to have an emergency shutdown system that when activated, immediately stops of the flow of propane.

These systems vary, so be sure you fully understand your plant’s emergency shutdown system and procedures.

Learn how to operate your plant’s emergency shutdown system and where to find shutdown locations, shutdown controls, and devices. Become familiar with evacuation procedures and routes from the transfer area.

Examine transfer bulkheads, emergency shutoff valves (ESVs), and operators such as cables and pneumatic devices that operate ESVs to ensure all are in good working condition. Never disable an ESV.

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LESSON 1


Emergency Shutdown Systems cont.

Check the location and condition of plant fire extinguishers.

Know your company’s policies and plant emergency procedures.

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LESSON 2

Filling a Bobtail Using a Plant Pump

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LESSON 2


Introduction

This lesson presents a 7-step procedure for loading a bobtail’s cargo tank using a plant pump:

Step 1: Prepare for the Loading Operation Step 2: Check the Liquid Level Gauges Step 3: Ensure Valves are Closed and Check Hoses Step 4: Connect the Transfer Hoses Step 5: Perform the Sniff Test Step 6: Fill the Cargo Tank Step 7: Disconnect Hoses and Prepare Bobtail for

Travel

These steps are commonly used in the propane industry, and follow U.S. DOT regulations, manufacturer’s instructions, and NFPA 58 provision. Because each bulk plant’s system and equipment are different in each bulk plant, always check with your supervisor.

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LESSON 2


Step 1: Prepare for the Loading Operation

When you first arrive at the bulk plant to load your bobtail:

Check for obstacles that might create an unsafe filling condition.

Ensure that the liquid fill connection on the cargo tank is at least 10 ft from the nearest bulk storage container. Always contact your supervisor to determine how to position your bobtail at the bulkhead in a way that maximizes the shearing effect of the hoses and piping in the event of a pull-away.

Set the parking brake and turn off the engine. Place chock blocks in front of and behind a rear wheel to

prevent the vehicle from rolling forward or backward. Remove any ignition sources within 25 ft of the transfer

point. Shut down any internal combustion engines within 15 ft of the transfer. Cease metal working operations (grinding, welding, brazing, etc.) within 35 ft of the point of transfer."

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LESSON 2


Step 2: Check the Liquid Level Gauges

First, check the liquid level gauges on the bulk plant storage tank to ensure that it has enough liquid propane to fill your cargo tank. If it does not, contact your supervisor or plant manager so they can set up delivery.

Also, check the liquid level gauges on your cargo tank and record how much propane is in the tank before beginning the loading operation.

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LESSON 2


Step 3: Ensure Valves are Closed and Check Hoses

Before connecting the hoses to begin loading operations, you must make sure all appropriate valves are closed and hoses are in good working condition.

Make sure the liquid fill and vapor equalizing valves on the cargo tank are closed. Remove the dust caps from the valves, inspect them for damage and wear, and if

necessary, replace defective gaskets. Make sure the bulk plant liquid and vapor hose-end valves are closed. Inspect the transfer hoses, couplings, valves, and connectors, including ACME

threads, to ensure they are free of defects or damage.

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LESSON 2


Step 3: Ensure Valves are Closed and Check Hoses cont.

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Ensure the liquid and vapor valves on the cargo

tank and the bulk plant are closed.

Inspect transfer hoses and system equipment for

damage.

LESSON 2


Step 4: Connect the Transfer Hoses

To properly connect the liquid transfer and vapor equalizing hoses:

Connect the plant liquid hose to the liquid fill valve on the bobtail cargo tank. Whenever handling the hose, be sure to point the end of the hose away from your body.

Tighten the plant liquid hose into the filler valve of the cargo tank by moving the hose assembly up and down while turning the ACME connector. Once the connection is hand tight, give it an additional quarter turn using a spanner wrench.

Connect the vapor equalizing hose between the storage container and the cargo tank and hand tighten so it doesn’t leak.

Note: In accordance with company policy, operate the ESVs at the loading bulkhead to be sure they are functioning properly. If they are not operating properly, do not connect the transfer hoses between the storage container and the cargo tank on the bulk delivery vehicle.

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LESSON 2


Step 4: Connect the Transfer Hoses cont.

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Connect and tighten the plant liquid hose to the

cargo tank liquid fill valve.

Connect and tighten the vapor equalizing hose

between the storage container and the cargo

tank.

LESSON 2


Step 5: Perform the Sniff Test

Before filling the cargo tank, your company may require you to perform a sniff test and verify product odorization. To do this:

Vent a small quantity of propane through the vent valve located on the plant liquid hose.

Sniff the area immediately after the liquid vaporizes.

If you can smell propane odorant, proceed with the loading operation.

If you cannot smell propane odorant or smell anything unusual, do not load the cargo tank. Contact your supervisor immediately and tell others in the area not to load until approved by the facility manager or supervisor.

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LESSON 2


Step 6: Fill the Cargo Tank

During the transfer operation, a qualified person must be in attendance at all times. To fill the cargo tank:

Insert a ticket in the plant meter and reset the register to zero if applicable. Ensure all liquid and vapor equalizing valves are fully open in the transfer

piping between the plant storage tanks and the bulkhead. Open the manual vapor equalizing valve and the manual filling valve on the

cargo tank. If you notice any leaks, close all valves, stop the process, and repair leaks before proceeding.

Start the pump and monitor the liquid level gauges. When the maximum permitted filling level is reached, immediately turn off the plant pump.

Close the plant liquid hose valve and all valves on the cargo tank.

Be alert for signs of erratic pump operation during the transfer. If a leak or fire develops during the transfer, close all ESVs immediately and stop the pump if you can do so safely. Move upwind and away from any uncontrolled release of propane.

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LESSON 2


Step 6: Fill the Cargo Tank cont.

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Ensure all liquid and vapor

equalizing valves are open.

Start the pump and monitor the liquid

level gauges.

Close the plant and cargo tank

valves.

LESSON 2


Step 7: Disconnect Hoses and Prepare Bobtail for Travel

When the loading operation is complete, do the following to prepare the bobtail for travel:

Bleed down and disconnect the plant liquid hose from the bobtail liquid fill connection.

Bleed down and disconnect the vapor equalizing hose from the vapor equalizing connection on the bobtail.

Replace the dust caps on the bobtail liquid fill and vapor equalizing connections. Replace the dust caps on the plant liquid and vapor hoses and store them as

required. Walk around the bobtail and check for any obstacles that may be in its path. Remove the chock blocks and stow them in their travel compartment or holders.

Move the vehicle but only after it has been determined the path is clear and discharge of propane has dissipated.

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LESSON 2


Step 7: Disconnect Hoses and Prepare Bobtail for Travel cont.

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Bleed down and disconnect liquid

and vapor equalizing hoses.

Replace all dust caps. Remove the chock blocks.


LESSON 3

Other Loading Methods

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LESSON 3


Other Loading Methods

Two other less-frequently used methods for loading a bobtail at the bulk plant are:

Vapor compressor method: Vapor compressors are more common in areas of extremely hot weather

Auxiliary pump inlet method: Auxiliary pump inlets are sometimes used when there is a power failure at the bulk plant.

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LESSON 3


Vapor Compressor

Vapor compressors remove vapor from the cargo tank, compress the vapor to a higher pressure, and move it through piping into the supply tank. The higher pressure in the supply tank forces liquid to move to the cargo tank where the pressure has been reduced by the vapor compressor. Here are a few guidelines to follow when using a vapor compressor to load your bobtail at the bulk plant:

Inspect the compressor and check the crankcase oil level in the sight glass, or by using the dipstick.

Open the vent on the compressor’s liquid trap to verify that liquid is not present in the vapor hose and suction line. Liquid can severely damage the compressor.

Verify the 4-way valve is in the proper position for loading the bobtail.

Operate the compressor in accordance with manufacturer's instructions.

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LESSON 3


Auxiliary Pump Inlet

Many bobtail pumps have an attached auxiliary pump inlet with a pipe, adapter, and shutoff valve. The auxiliary pump inlet can be used to move liquid propane into the bobtail pump from a bulk plant storage tank during a power outage.

Follow these guidelines when using an auxiliary pump inlet:

Follow the bobtail’s operating instructions and see your supervisor for self-loading procedures.

Become familiar with the liquid internal valve operation.

Ensure that the pump-actuated pressure differential internal valve remains in the closed position before and after the PTO is engaged.

Follow PTO operating procedures for the bobtail.

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LESSON 3


Summary

Some important points to remember from this module are:

Before beginning loading operations, be sure you understand the bulk plant’s layout, equipment, and piping configuration.

Emergency shutdown systems vary from one plant to the next so you need to understand how each one operates, where the controls are located, and evacuation routes.

Follow important safety steps when getting ready to load. Position your bobtail at the bulkhead, set your parking brake, put out chock blocks, and remove ignition sources from the transfer area.

Always make sure cargo tank and hose-end valves are closed before connecting hoses. Remain in attendance during the entire transfer operation.

After loading, prepare the bobtail for travel by bleeding down and disconnecting all hoses and doing a quick walk-around of the bobtail.

Always be prepared. Know how to load with a plant compressor or auxiliary pump inlet.

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BOBTAIL DELIVERY OPERATIONS MODULE 3 Bobtail Equipment and Systems 1