HazMat/WMD Technician for Surface Transportation Training Support Package November 2014 Module 18: Highway Cargo Tanks

HazMat/WMD Technician forSurface Transportation

Training Support Package

November 2014

Module 18: Highway Cargo Tanks

HazMat/WMD Technician for Surface Transportation

Introduction

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This module provides information about the types of highway cargo tanks and tube trailers along with their configurations and safety features.


Enabling Learning Objectives

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18-1 Identify and describe the hazards associated with:

− MC 306/DOT 406 cargo tanks− MC 307/DOT 407 cargo tanks− MC 312/DOT 412 cargo tanks − MC 331 cargo tanks− MC 338 cargo tanks− Non Specification

• Cryogenic• Dry bulk cargo tanks• Tube trailers



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18-2 Identify the capacity (by weight and volume) of each of the above tanks/trailers, using the DOT specification plate. 18-3 Identify the basic design and construction features of each, and what each carries 18-4 Identify the closures found on each, including their names and functions.



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18-5 Identify the required tank identification and other markings.18-6 Identify the location and use of the mechanical, hydraulic, and air emergency remote shut-off devices found on MC 306/D0T 406, MC 307/DOT 407, MC 312/D0T 412, MC 331, and MC 338 cargo tanks.18-7 Given a HazMat/WMD highway incident, demonstrate the methods for controlling releases from cargo tanks.


Definition of a Cargo Tank

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• Tank intended to carry liquids or gases• Fittings, closures, reinforcement• Part of motor vehicle during transportation, loading and unloading• Not a cylinder or portable tank


Spec / Non-Spec

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• Code of Federal Regulations Title 49

• Bureau of Explosives 6000

• Non-specs may resemble spec tanks

• Almost all HazMat must be carried in specification containers


Cargo Tank

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MC 306 DOT 406

MC 307 DOT 407

MC 312 DOT 412

MC 331

MC 338

Post August 31, 1995, DOT Specifications

MC vs. DOT


DOT 400 vs. MC 300

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• Thicker shells

• Reinforced rollover protection

• Manhole pressure capacity

• Self-reclosing fittings


DOT Specs MC300/DOT400

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Construction Material-A bulk liquid cargo tank may be: • Aluminum alloy• Mild steel• Stainless steel• Carbon steel• Carbon steel with a liner• Container must meet CFR 49 standards


Structural Components

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Circumferential reinforcement-• A cargo tank may or may not have a frame.• Normally shells serve as trailer frame• Less than 3/8” require reinforcement• Bulk head - single and double• Baffle - side drains• Ring stiffeners• Maximum unreinforced span - 60”• Incompatible may not be hauled in same tank


Double Bulkhead

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Weep Hole

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Baffle

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Ring Stiffeners

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Protection Against Damage

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Cargo tanks hauling HazMat also must provide protection against accidental damage:

• Mounting pads

• Rollover protection

• Pressure venting features

• Protection of bottom outlets

• Bumper protects rear mountings


Mounting Pads

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Rollover Protection

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Pressure Venting

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Outlet Protection

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Bumper

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Emergency Devices

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• Sheer protection

• 70% strength of piping

• Fusible / frangible devices - 250oF MAX

• Rollover protection

• Internal valves

• Remote Emergency Closing Actuator


Emergency Discharge Control

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Remote Closing Activator- The location of the Emergency Remote Shut off will vary from one DOT spec cargo tank to another, if required.Under normal conditions, the valves operate either:− Mechanically− Hydraulically− Pneumatically


Mechanical Emergency Shut-off

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• A clamping nut and fusible bushing (< 250oF), attach each cable to its handle• Two Trip lever –

− One on left side− One at control handle


Hydraulic Emergency Shut-off

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• Manual pump opens and hydraulic emergency valve• Releasing closes the valve• The frangible part must be broken manually• The fusible part operates (< 250oF)


Pneumatic Emergency Shut-off

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• Emergency valves operate essentially like hydraulic valves only with air• A remotely located fusible and frangible plug• The fusible part of the operates (< 250oF)


Tank Pressure Requirements

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• MAWP - Maximum Allowable Working Pressure

• Service or design pressure• External design pressure• Test pressure - 1.5 to 2 times service• Valves and vents


Specification Plate

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• Vehicle manufacturer• Vehicle Serial Number• Lining material (if any)• Date of manufacture• Certification date• Design service temp.• Test pressure• Maximum weight of lading• Design weight of lading


MC 306

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• Transports petroleum• Capacities up to 10,000 gallons.• Oval Cross-section• Full-length rollover protection• Man ways and dome lids - most common leak is in the dome lid.


MC 306

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• Some made of carbon steel• Most made of .25- inch thick aluminum alloy. • One to eight compartments• Most common four to five


MC 306

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• Low pressure vessel• MAWP is 3 psig.• Internal emergency shut-off valves usually mechanical/ pneumatic − Driver's side at the

front of the tank− Control handle at

valve


MC 306 Vents

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• Pressure-activated vent vacuum to 1 psig and pressure to 3 psig• Fusible element <250°F or less installed insufficient to vent 6,000 cubic feet of vapor at 5 psig.• "Scully" or overfill protection fails• Push vent


DOT 406

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• Oval in cross-section. • Thicker shell and head add from 300 to 400 pounds• Tank pressure MAWP min. 2.65 psig and max. 4 psig• Relief valve pressure settings- 125% MAWP or 3.3 psig


DOT 406

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• Vacuum relief device opens at no more than 6 ounces vacuum and limit vacuum to 1 psig.• Manhole-assembly affects integrity, a static internal fluid pressure greater than the tank's test pressure or 36 psig. May not have a fusible vent.


MC306/DOT 406-Never Try To Lift

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• Ground and bond, drill ,Stinger, off load• Control leaks from dome lids• Vapor suppression


MC306/DOT 406

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MC306/DOT 406

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MC307

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• Workhorse of chemical industry• Usually stainless steel • Cap. 5,000 to 7,000 gal.• Round cross-section • Insulated or non- insulated• 1 to 4 compartments • 1 to 2 common• Leaks commonly occur -manway and safety relief device.


MC307 Structural Features

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• External ring stiffeners and in multi-compartment tanks, bulkheads provide reinforcement • Internal baffles rarely are used• Rollover protection twice the weight of the loaded tank and a horizontal load of half the weight of the loaded tank. • An insulated will have 5" of fiber glass held with stainless steel panels. • Coils are connected to the tractor's cooling system


MC307

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• Tank pressure MAWP a min. 25 psig.• Working pressure over 50 psig• Tank must meet

requirements of the American Society of Mechanical Engineers .


MC307-Loading and Un-loading

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• Loaded through the manway or bottom internal valves• Load or unload from rear of the tank• Center un-loaders (belly unloading, tanks with multiple compartments)• Single shot MC 307 tanks


MC307-Valves and Vents

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• Internal emergency shut-off valves - self- closing internal emergency shut-off valve.• Safety relief valves• Spring-loaded, pressure-activated vents


DOT407

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• Thicker shell and head• Adds approx. 800 lbs. to an average 5,000-7,000 gallon, aluminum alloy tank. • Requires increased overturn protection • May be designed for vacuum service (vacuum loading). • Vacuum service must meet minimum external design pressure standards.


DOT407-Tank Pressure

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• Minimum MAWP (25 psig)• ASME apply to any with a minimum internal MAWP over 35 psig (15 psig lower than for the MC 307)• Loaded by vacuum minimum external design pressure must be 15 psig.


DOT407- Safety Relief Devices

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• Primary pressure relief one or more reclosing pressure- relief valves. • Can use a non-reclosing pressure relief device ONLY as part of a series which includes a reclosing pressure relief device• A frangible disc only between product and telltale indicator• Primary relief valve must be at least 120% of the MAWP and not over 132% of the MAWP.• Secondary relief valve must be at least 120% of the MAWP.• Manholes- must withstand the greater of 40 psig or the tank's test pressure


MC312

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• Primarily transport corrosive products acids and bases (caustics). • Made of:− Mild steel− High strength low alloy

steel− Stainless steel− Steel with a lining• Average capacity of 3,000 to 5,000 gallons.


MC312Structural Features

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• Round cross-section• Commonly single- compartment• One to four compartments• Each have own manway. • Use external ring stiffeners as reinforcement• Insulated or non-insulated• May be lined or unlined• Usually are clean bore, for easier cleaning



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• Smaller diameter, (greater specific gravity of products)• Usually top service. • Bottom outlets are not common. • Protective coating on manway, valve assemblies and tank • Leaks common around the manway and bottom sump.



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• Linings• Leaks migrate• Bonded linings• 10 years service• Pressure ratings determined by product unloading, over 15 psi ASME must certify


MC312

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• Unloading either top or bottom• Each outlet at or near the top of the tank must have an external shut-off valve as close to the tank as possible.• Top of the tank, an eduction line extends (sump) shut-off valve is at the top of the tank.• For pressure unloading from the bottom, an internal emergency shut-off valve must be installed in the bottom outlet.


MC312

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• Remote closures must be 10 feet away• Blind flange, sealing cap, or shut-off valve at end of the outlet. • Safety venting devices must activate at a pressures not over 150% of design pressure• Pressure unloading, the relief valve limit the tank pressure to 130% of valve's design pressure for maximum air flow [Sec. 178.343-4(a)].


DOT412

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• The minimum internal MAWP not designed to be loaded by vacuum pressure is 5 psig.• Loaded by vacuum press. min. of 25 psig internal and external press. min. of 15 psig.• External design pressure of 15 psig or more must be circular in cross-section• Some may be oval.• Pressure reliefs on DOT 412s are like those on the DOT 407 [Sec. 178.345-10(1)].


Multi-purpose Cargo Tanks

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• The vents and reliefs that require changing must be stamped with the appropriate MC specification number and color-coded:− MC 306 red− MC 307 green− MC 312 yellow− Non-specification-blue• Multipurpose cargo tanks are not common and the 400 series prohibits them.


MC331

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• Rounded ends• 8,000 - 11,500 gallons• Normally one compartment• Liquefied compressed gas• Steel or aluminum may be insulated• ASME-MAWP 100-500 psig• Upper two-thirds of tank painted white or of a reflective material


MC331

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• Valves protected• Openings must be plugged, capped, or bolted flange• Protected with an excess flow valve on product discharge openings or backflow check valve on product inlet openings• Fitted with an internal self-closing stop valve • Each Cargo Tank inlet and outlet must be marked liquid or vapor when the tank is filled


MC 331 Safety Devices

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• <3,500 gallons, at least one emergency discharge control (remote closing activator)• > 3,500 gallons two emergency discharge controls (remote closing activators)• Excess flow valves must close automatically backflow check permit flow only in one direction.• Safety relief pressure discharge 110% not to exceed 120%


MC331-Markings

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• Stenciled with the proper shipping name must appear on the sides and ends of the tank.• QT (Quenched & Tempered) or NQT (Not Quenched and Tempered)• QT or NQT appears above or next to the specification plate.

• "NQT" are authorized for all grades of anhydrous ammonia. • "QT" are authorized for anhydrous ammonia having a minimum water

content of 0.2% by weight.• NQT steel are authorized to carry all grades of LPG• QT steel can carry only grades of LPG that are determined

"noncorrosive"


MC338

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• 8,000 - 10,000 Gallons• Pressures 25.3 psi - 500 psi• Design Service Temperature• Left front pressure gauge, rear view• Cryogenics under -130oF Boiling Temp• Vacuum and Insulated• Emergency controls same as MC331• Thermal closure at a temp. not over 250oF


Non-spec Cryogenic

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• Carry atmospheric gases (oxygen, nitrogen, and helium) • Don't have all the safety features of an MC 338. • Bleed off excess pressure during transport• Special regulation for carrying a cryogenic flammable liquid-No carrier may operate and no driver may drive a motor vehicle transporting a flammable cryogenic liquid in a package exceeding 125 gallons unless written instructions accompany the package. • The instructions must contain with required shipping papers:

− General precautions− Manual venting instructions− Emergency procedures− The names and telephone numbers of contact in an emergency.


Specification Plate MC338

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• Vehicle manufacturer• Vehicle Serial Number• Lining material (if any)• Date of manufacture• Certification date• Design service temperature• Insulation for Oxygen Service or Not Authorized for Oxygen

Service• Maximum weight of lading• Marked holding time• Design weight of lading

MC 338s carrying flammable cryogenic liquids must be marked on the right side, in letters at least two inches high, as follows:ONE-WAY TRAVEL TIME :_________HRS with the blank filled in with the number of hours.


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Non-specification Cargo Tanks

• Asphalt trailers• Pneumatic Dry Bulk• Tube trailers• Vacuum Trucks


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Asphalt Trailers


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Dry Bulk Materials• Transport dry bulk materials• Manufactured

– Aluminum and mild steel– Operates on pressure up to 15 psi– Blower may be located on trailer– May be gravity unloaded

• Valves– Back flow valves– Blow down valve


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Tube Trailer – Non Spec Trailer• Each cylinder is a

separate DOT spec. cylinder– Manifolded together– Compressed

gases only– 2500 psi and higher

• Venting must be unobstructed and not impinge on other containers


Vacuum Trucks

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Conclusion

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• Participants were given information to provide the ability to:− Identify and describe the hazards associated with:

• MC 306/DOT 406 and MC 307/DOT 407 cargo tanks• MC 312/DOT 412 cargo tanks • MC 331 cargo tanks and MC 338 cargo tanks• Non-specification

− Asphalt− Dry bulk cargo tanks− Tube trailers

• Demonstrate how each of the above differs and how to respond using control measures, valve operation and safety systems.

Documents

HazMat/WMD Technician for Surface Transportation Training Support Package November 2014 Module 18: Highway Cargo Tanks