# Manufacturing Cost Estimation for Class 2B/3 CNG SystemsEPA-420-D-15-004

June 2015 NOTICE

This technical report does not necessarily represent final EPA decisions or positions. It is intended to present technical analysis of issues using data that are currently available. The purpose in the release of such reports is to facilitate the exchange of technical information and to inform the public of technical developments. Assessment and Standards Division Office of Transportation and Air Quality U.S. Environmental Protection Agency

Prepared for EPA by
FEV North America, Inc.

EPA Contract No. EP-C-12-014 WA2-03 

# Manufacturing Cost Estimation for Class 2B/3 CNG SystemsAnalysis Report BAV-P310324- 03 June 26, 2015 Page 3 

### Table of Contents

Executive Summary 7

1. Introduction and Program Objectives 8

1.1. Objective 8

1.2. Vehicle Selection 8

1.3. Background 8

2. System Overview & Cost Structure 11

2.1. System Design 11

2.2. Hardware 13

2.3. BOM Creation 15

2.4. Costing Methodology 17

3. Storage Subsystem 18

3.1. Tank Cover Sub-Subsystem 18

3.2. Cradle Sub-Subsystem 21

3.3. Tank Sub-Subsystem 23

4. Safety Devices Subsystem 30

4.1. High Pressure Lock-Off Valve Sub-Subsystem 30

4.2. Safety Relief Valve Sub-Subsystem 33

4.3. Excess Flow Valve Sub-Subsystem 35

4.4. Purge Sub-Subsystem 38

5. High Pressure Circuit Subsystem 39

5.1. Filler (Refueling) Sub-Subsystem 39

5.2. Distribution, High Pressure Sub-Subsystem 41

5.3. Filter Sub-Subsystem 42

5.4. Pressure Regulator Sub-Subsystem 44

6. Low Pressure Circuit Subsystem 45

6.1. Distribution, Low Pressure Sub-Subsystem 45

6.2. Fuel Rails Sub-Subsystem 47

6.3. Fuel Injector Sub-Subsystem 48

7. Controls Subsystem 50

7.1. Control Module Sub-Subsystem 50

7.2. Wire Harnesses Sub-Subsystem 53

8. Cost Summary and Conclusion 54

9. Appendix A 57Analysis Report BAV-P310324- 03 June 26, 2015 Page 4 

### List of Figures

Figure 1- Chevrolet Silverado 2500 CNG 8

Figure 2- Compressed Natural Gas (CNG) System 12

Figure 3- CNG System Hardware 14

Figure 4- Storage Subsystem 18

Figure 5- Tank Cover Sub-Subsystem – Assembled 19

Figure 6- Tank Cover Sub-Subsystem – Components 20

Figure 7- Cradle Sub-Subsystem – Components 21

Figure 8- CNG Tank 23

Figure 9- CNG Tank Label 24

Figure 10- Silverado CNG Tank Section # 1 24

Figure 11- Silverado CNG Tank Section # 2 25

Figure 12- Step 1: Seamless Aluminum Tube Cut to Length 26

Figure 13- Step 3: Preheating of Blank Prior to Spin Form 26

Figure 14- Step 4: Blank Chucked in Spin Form Machine 27

Figure 15- Step 4-1: Spin Forming 27

Figure 16- Step 4-2: Spin Forming 28

Figure 17- Step 5: Heat Treatment (Stress Relief) 28

Figure 18- Step 8: Carbon Fiber Wrapping 29

Figure 19- Step 8: Carbon Fiber Wrapping (Continued) 29

Figure 20- High Pressure Lock-Off Sub-Subsystem – Assembled 31

Figure 21- High Pressure Lock-Off Sub-Subsystem – Components 31

Figure 22- High Pressure Lock-Off – Exploded View 32

Figure 23- Safety Relief Valve – Assembled 33

Figure 24- Safety Relief Valve – Components 34

Figure 25- Safety Relief Valve – Exploded View 34

Figure 26- Excess Flow Valve – Assembled 36

Figure 27- Excess Flow Valve – Exploded 36

Figure 28- Purge Sub-Subsystem – Components. 38

Figure 29- Filler Sub-Subsystem – Components 39

Figure 30- Fill Port – Exploded View 39

Figure 31- Distribution, High Pressure Sub-Subsystem 41

Figure 32- Filter Sub-Subsystem – Components 42

Figure 33- CNG Filter – Exploded View 42

Figure 34- Pressure Regulator Sub-Subsystem – Components 44

Figure 35- Pressure Regulator – Exploded View 44Analysis Report BAV-P310324- 03 June 26, 2015 Page 5 Figure 36- Distribution, Low Pressure Sub-Subsystem – Components 46

Figure 37- Fuel Rails Sub-Subsystem – Compon ents 47

Figure 38- Injector Nozzle – Components 47

Figure 39- Fuel Injector Sub-Subsystem – Components 48

Figure 40- CNG Fuel Injector – Sectioned 49

Figure 41- Control Module Sub-Subsystem – Components 50

Figure 42- CNG ECU – Exploded View 50

Figure 43- CNG ECU Board with Circuit ID numbers – Top 51

Figure 44- CNG ECU Board with Circuit ID numbers – Bottom 52

Figure 45- Wire Harness Sub-Subsystem 53

Figure 46- CNG Subsystems 55

Figure 47- Manufacturing and Mark-up Cost 55Analysis Report BAV-P310324- 03 June 26, 2015 Page 6 

### List of Tables

Table 1- U.S. Product Supplied of Finished Motor Gasoline 9

Table 2- U.S. Alternative Fueling Stations by Fuel Type 10

Table 3- BOM Compressed Natural Gas (CNG) System 16

Table 4- BOM Tank Cover Sub-Subsystem 20

Table 5- BOM Cradle Sub-Subsystem 22

Table 6- BOM CNG Tank Sub-Subsystem 30

Table 7- BOM High Pressure Lock-Off Valve Sub-Subsystem 32

Table 8- BOM Safety Relief Valve Sub-Subsystem 35

Table 9- BOM Excess Flow Valve Sub-Subsystem 37

Table 10- BOM Purge Sub-Subsystem 38

Table 11- BOM Filler (Refueling) Sub-Subsystem 40

Table 12- BOM Distribution, High Pressure Sub-Subsystem 41

Table 13- BOM Filter Sub-Subsystem 43

Table 14- BOM Pressure Regulator Sub-Subsystem 45

Table 15- BOM Distribution, Low Pressure Sub-Subsystem 46

Table 16- BOM Fuel Rails Sub-Subsystem 48

Table 17- BOM Fuel Injectors Sub-Subsystem 49

Table 18- BOM Control Module Sub-Subsystem 52

Table 19- BOM Wire Harnesses Sub-Subsystem 53

Table 20 - CNG Subsystem Cost Summary Overview 54

Table 21 - Complete Cost Summary (CMAT) – CNG System 57Analysis Report BAV-P310324- 03 June 26, 2015 Page 7 

### Executive Summary

The United States Environmental Protection Agency (EPA) contracted with FEV North America, Inc., to determine incremental direct manufacturing costs for a complete CNG fuel system. The system selected to represent the light-duty vehicle segment was a 2013 Chevrolet Silverado equipped with General Motors Bi-Fuel option. The Silverado was purchased by FEV and all CNG related components were identified. The vehicle was then completely disassembled. Names, photos and weights were assigned to all CNG related components and compiled in a Bill of Materials (BOM)

. All CNG system components were reviewed in detail and cost estimated using FEV’s standard costing process. All costs were developed using a volume assumption of 450,000 units per year. This cost analysis is inclusive of all associated assembly cost from component to

vehicle. Calculations were performed to determine equipment sizing, cycle times and material usage requirements. FEV utilized its extensive database of rates for equipment, labor, material, end item scrap, selling, general and administrative (SG&A ), profit, and engineer i ng , design and testing (ED&T) to develop costs representative of what an OEM would incur for such a system in high volume automotive manufacturing.

Cost for the five (5) subsystems are as follows:

1. Storage-$1,360

2. Safety Devices- $151

3. High Pressure Circuit-$184

4. Low Pressure Circuit- $278

5. Controls-$303

Total System cost = $2,276

Sixty (60) percent of the system cost can be attributed to CNG storage. Gasoline’s 17x energy density factor over natural gas at atmospheric conditions creates a storage challenge for CNG

. High pressure storage (3600psi) is required to minimize this energy density differential. Pressure, weight, and safety requirements all contribute to CNG tank costs. The one-piece, seamless, carbon fiber reinforced tank undergoes a twelve ( 12 ) step manufacturing process before completion. In light of carbon fiber processing improvements like pre-preg fibers, the process of wrapping is a time consuming cost driver. Make up 44% of the tank cost. The wrapping process and material cost of

carbon fiber.

The System is comprised of: high pressure lock-off, pressure relief device, and excess

flow valve. High Pressure Circuit includes; refueling filler, fuel lines, filter and pressure regulator. Low Pressure Circuit includes; fuel lines, fuel rails and CNG injectors. Controls include; ECU, intake air temperature module, fuel pump module, and wiring.

General Motors Bi-Fuel System was designed as an add-on to an existing gasoline engine. As an add-on, the CNG system has its own ECU requiring Intake Air Temperature and Fuel Pump control modules. A dedicated CNG system would eliminate these components, reducing overall vehicle cost.Analysis Report BAV-P310324- 03 June 26, 2015 Page 8 

### 1. Introduction and Program Objectives

1.1. Objective

The objective of this study is to develop cost for a complete light-duty truck CNG system, manufactured at high production volume (450,000 units per year).

1.2. Vehicle Selection

A 2013 Silverado 2500 4WD LT Extended CAB truck with bi-fuel option was selected as a representative light-duty passenger vehicle CNG system. The truck was equipped with a 6.0L Vortec engine, GM designation LC8. The CNG system is modular and was designed as an add- on op tion to GM’s existing product.

Figure 1- Chevrolet Silverado 2500 CNG

(Source: FEV, Inc. photos)

1.3. Background

For the same energy output, combustion of CNG produces 29% less carbon dioxide than combustion of oil base fuels (i.e., gasoline). ‘In most applications, using natural gas produces less of the following substances than oil or coal: carbon dioxide (CO2), the primary greenhouse gas; sulfur dioxide, which is the primary precursor of acid rain; nitrogen oxides, which is the primary precursor of smog; and particulate matter, which can affect health and visibility .’Analysis Report BAV-P310324- 03 June 26, 2015 Page 9http://www.aga.org/ourissues/issuesummaries/Pages/EnvironmentalBenefitsofNaturalGas.aspx

In 2013 the US consumed 3.2 billion barrels of gasoline as shown in Table 1 . In addition to fuel reduction technologies like turbo-downsizing and lightweighting, CNG offers another option to reducing petroleum-based fuel consumption.

Table 1- U.S. Product Supplied of Finished Motor Gasoline

http://www.eia.gov/tools/faqs/faq.cfm?id=23&t=10

‘CNG conversions can provide stability against fluctuating fuel prices as well as lower vehicle operating costs for fleet administrators. CNG sells for an average of $2.10 per Gasoline Gallon Equivalent (GGE), and is as low as $1 in some parts of the country, representing a significant savings over unleaded regul ar fuel. The national price range

fo r unleaded regular fuel is $2.25 - $3.50 per gallon’.

http://corporate.ford.com/news-center/press-releases-detail/first-cng-capable-2014-fordf-150-rolls -off-the-line- in -kansas

Storing enough natural gas in a motor vehicle to provide a sufficient range is a challenge with CNG. To improve upon its lower energy density, natural gas is stored at 3600 psi. Even at this pressure fuel tank size is significantly larger. For example the Silverado CNG tank is rated at 17 GGE gallons however, the actual internal tank volume as measured after sectioning by FEV is approximately 55 gallons. G GE is based on an equal measure of energy making it possible to compare cost per unit of alternate fuels, GGE in terms of CNG Gas (Volume/Pressure/Temp) = 1 Gallon of Gas (Temp, Pressure=atm)

. For example 1 GGE of CNG and 1 gallon of gasoline are equivalent.

At this time, the primary drawbacks of CNG are the underdeveloped vehicle refueling infrastructure and the fuel storage requirements. As of 2013 there were approximately 1,260 CNG refueling stations in the country.Analysis Report BAV-P310324- 03 June 26, 2015 Page 10

Table 2- U.S. Alternative Fueling Stations by Fuel Type

http://www.afdc.energy.gov/data/10332

Implementing a high pressure CNG system in a passenger vehicle requires safety provisions not needed with conventional gasoline. Directly mounted to the CNG tank are two (2) safety devices. The first is an electronic flow lock preventing CNG from leaving the tank unless permitted by the ECU. The second is a pressure relief valve with back-up burst disc to prevent overpressure in the CNG system. A manual isolation

valve is located after the tank for service and an additional electronic flow lock is located in the pressure regulator. A flow fuse is used to cut-off flow in the event the system is ruptured and the intended gas flow rate is exceeded.

Higher combustion temperatures and corrosive properties of natural gas require

hardened exhaust valves and intake/exhaust valve seats.

http://www.gmfleet.com/vehicle-overviews/fuel-efficiency/bi-fuel.htmlAnalysis Report BAV-P310324- 03 June 26, 2015 Page 11 

### 2. System Overview & Cost Structure

2.1. System Design

Figure 2 is a schematic representation of the CNG system generated as an aid to understand the components and their function. The system was broken into five (5) subsystems and color coded at the bottom of the figure. The CNG tank manages fuel pressures up to 3600 psi when full. Directly mounted to the CNG tank are the Safety Relief Valve and High Pressure Lock-off (HPL) solenoid.

Connecting to the underbody purge line is the safety relief assembly. A spring piston with plastic face seal opens when the tank pressure exceeds the design limit. Over temperature conditions exceeding the melting point of the plastic face seal will also open this valve. The pressure burst disc is a secondary safety device protecting the tank from over pressure.

The opposite end of the tank mounts the HPL solenoid. This valve requires activation

befor e any

gas is permitted to exit the tank. Integrated into this assembly is a manual purge valve, providing a means to vent the system to the atmosphere, and a temperature transmitter extending into the tank cavity.

Following the HPL solenoid is the excess flow valve. This device protects the system

from a downstream rupture. If the gas flow exceeds the limit of this valve it closes. When pressure across the valve equalizes the valve automatically resets.

The fill circuit consists of a quick release with integrated check valve for ensuring oneway flow. The quick release serves as the connection point for refueling. A secondary check valve located after the quick release again ensures one-way flow. The fill circuit continues to the tank with reverse flow through both the excess flow valve and HPL

solenoid.

Continuing from the excess flow valve, fuel travels through a manual ball (service) valve

to the filter before entering the pressure regulator. Integrated into the pressure regulator is a normally closed solenoid valve in addition to pressure and temperature transmitters. The solenoid valve provides another level of security from unintended fuel flow. Heat absorption caused by the expansion of gas requires a heating circuit which ties into the engine cooling system. The pressure regulator reduces pressure to 100 psig.

Following the pressure regulator, fuel is routed to the fuel rails supplying eight (8) individual CNG injectors. The injectors terminate via hose to port mounted nozzles in

the intake manifold.Analysis Report BAV-P310324- 03 June 26, 2015 Page 12

Figure 2- Compressed Natural Gas (CNG) System

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 13

2.2. Hardware



### Primary CNG hardware is shown in Figure 3 

### in order as follows:

 Type 3 CNG Tank

 Manufacturer: Structural Composites Industries; P/N:319875

 Construction: Seamless Aluminum, Carbon Fiber reinforced

 High Pressure Lock-Off ( HPL )

 Manufacturer: GFI Control Systems; P/N:PT13F0172

 Construction: Billet Aluminum

 Features: Temperature Measurement, Manual Purge Valve

 Pressure Relief Device ( PRD )

 Manufacturer: GFI Control Systems; P/N:PRD-120BD

 Construction: Billet Aluminum

 Flow Fuse

 Manufacturer: HOKE; P/N:HVX316

 Construction: 316 stainless steel, brass, Monel ® , Hastelloy ® C- 276

 Distribution Lines

 Seamless Stainless Steel & Stainless Steel Jacketed PTFE

 Filter

 Manufacturer: Parker; P/N:FFC-112 SAE- 10

 Construction: Billet Aluminum, Coalescing Media Filter

 High Pressure Regulator ( HPR )

 Manufacturer: GFI Control Systems; P/N:P214- 980

 Construction: Forged Aluminum

 Features: High Pressure Shut-Off Solenoid, High Pressure Transducer, MAP
referencing

 Fuel Rail

 Billet Aluminum

 Fuel Injector

 Manufacturer: AC Delco; P/N:22991067

 Engine Control Unit ( ECU )

 Manufacturer: Fly SF; P/N:028705/9-V

 Control Modules – Intake Air Temperature ( IAT ), Fuel Pump

 Manufacturer: IMPCO Automotive; P/N: MD-53497-001, MD-54548- 001

 WiringAnalysis Report BAV-P310324- 03 June 26, 2015 Page 14

Figure 3- CNG System Hardware

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 15
2.3. BOM Creation

The CNG system was disassembled starting with the tank, following the flow path, and ending with the fuel injectors. Assemblies were removed from the vehicle in groups that were thought to represent actual assembly. After removal from the vehicle assembles/components were photographed, weighed and tagged.

The first step in disassembly of the CNG system was to purge all CNG from the tank.

This was done by releasing the manual purge valve and deactivating the solenoid lockoff valve. Next, the tank, cradle and related hardware were removed from the bed of the truck. Subsequently in conjunction with another study the entire truck was disassembled and all CNG related system components were removed, named, photographed, weighted and logged into a Bill of Material (BOM).

The CNG system was categorized into five (5) main Sub-Systems: Storage, Safety Devices, High Pressure Circuit, Low Pressure Circuit, and Controls. The storage subsystem includes the tank cover, tank cradle, and tank. The Safety Devices subsystem includes the high pressure lock-off, high pressure relief device, and excess flow valve. The high pressure circuit includes all high pressure fuel lines as well as fuel filter and pressure regulator. The low pressure circuit includes all low pressure fuel lines as well as cooling lines associated with the pressure regulator heating circuit. Also included in this subsystem are the fuel rail and fuel injectors. The wiring harness,

control modules and ECU are included in the Controls Subsystem.

The BOM structure shown in Table 3 details the subsystems and Sub-Subsystems which can be identified in the system schematic as segregated color shaded areas. The ‘Purge’ and ‘Distribution, Low Pressure’ Sub-Subsystems are shaded darker to highlight included plumbing.

Every Sub-Subsystem, assembly, or component listed in the BOM features: mass, photo link, cost, and quote link.Analysis Report BAV-P310324- 03 June 26, 2015 Page 16

Table 3- BOM Compressed Natural Gas (CNG) SystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 17 2.4. Costing Methodology

This cost analysis is a full system complete evaluation inclusive off all hardware associated with the CNG system. Included in the cost is component assembly to thevehicle. The CNG system as analyzed is a low-volume design, often utilizing off-theshelf hardware. On specific components, where a high volume manufacturing choice was clear, alternative manufacturing assumptions were made. For example, the safety relief protection collar was manufactured from billet however it was quoted as a die casting. Such assumptions are noted in detail throughout the body of this report. The volume assumption for cost estimation was 450,000 vehicles per year.

Costs were developed for all critical components by detailing each operation in a Manufacturing Assumptions Quote Sheet (MAQS). Process calculators were used to determine equipment size and corresponding rate ($/hr), cycle time (seconds) and material usage (kg). For example, the Pressure Regulator Cap was identified as an aluminum die casting. The number of slide pulls, cavities, part width, part height, average wall thickness, parting line area, cavity surface area, and max wall thickness were all used to determine the die-casting machine size, cycle time and material usage. This information was then transferred to the MAQS where rates are pulled in for material, labor, manufacturing overhead/burden, end item scrap, SG &A , profit, and

ED&T. Cost contributions are then calculated for these core cost elements. Similar process calculators are used for subsequent processing such as machining, where all machine features are measured, speed and feed rates assigned based on the respective material, and feed times calculated. In addition pallet changes, tool changes, rapid times, as well as estimated work pieces per fixture are used to estimate the total cycle time. Finally all processes are summed, end item packaging estimated, and total

cost calculated. Cost contributions for the core cost elements are then linked to the Cost Model Analysis Template (CMAT). The CMAT incorporates cost data from various Sub-Subsystems into one summary sheet. Process costs were estimated as follows:

1. Detailed assessment of manufacturing processes used to create the component

2. Populate appropriate process calculator, identifying equipment size, cycle time,
and material usage

3. Transfer data from step 2 into quotation sheet and assign labor resources

4. Repeat for all manufacturing processes required

5. Repeat for all components in Sub-Subsystem

6. Evaluate Sub-Subsystem assembly requirements including: number of stations,
level of automation, burden rate, number of operators, and cycle time

7. Evaluate vehicle assembly requirements including: number of stations, level of
automation, burden rate, number of operators, and cycle time

8. Assess packaging needs and estimate packaging costsAnalysis Report BAV-P310324- 03 June 26, 2015 Page 18 

### 3. Storage Subsystem

The storage subsystem includes all hardware associated with the CNG tank. It is subdivided into the following Sub-Subsystems:

 Tank Cover Sub-Subsystem

 Cradle Sub-Subsystem

 Tank Sub-Subsystem

Figure 4- Storage Subsystem

(Source: FEV, Inc. photos)

3.1. Tank Cover Sub-Subsystem

Figure 5 shows the tank cover as assembled in the bed of the Silverado. The cover

fastens to the cradle and cover mount bracket.Analysis Report BAV-P310324- 03 June 26, 2015 Page 19

Figure 5- Tank Cover Sub-Subsystem – Assembled

(Source: FEV, Inc. photos)

The Tank Cover Sub-Subsystem includes the fabricated diamond plate aluminum tank cover with access door, steel bracket, and associated fasteners as shown in Figure 6

. For high volume production the Tank Cover was estimated as multiple stampings assembled as a weldment. The cover mount was heavy gauge material and also processed as a multiple stamping weldment.Analysis Report BAV-P310324- 03 June 26, 2015 Page 20

Figure 6- Tank Cover Sub-Subsystem – Components

(Source: FEV, Inc. photos)

The bill of materials for Tank Cover Sub-Subsystem is shown in Table 4 . SubSubsystem mass is 33.7 kg and the cost is $94.

Table 4- BOM Tank Cover Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 21 3.2. Cradle Sub-Subsystem

The Cradle bolts into the box of the truck and serves as a mounting structure for the tank. The tank is secured to the cradle with two (2) rubber lined straps fastened with bolts. Cradle Sub-Subsystem components are shown in Figure 7

.

Figure 7- Cradle Sub -Subsystem – Components

(Source: FEV, Inc. photos)

The Cradle Sub-Subsystem is a weldment of thirteen ( 13 ) individual stampings. Three (3) sprung retaining mechanisms were used to attach the cradle to the back of the truck box. These retainers were estimated by assuming a clipnut for high volume production.Analysis Report BAV-P310324- 03 June 26, 2015 Page 22 The bill of materials for the Cradle Sub-Subsystem is shown in Table 5 . SubSubsystem mass is 78.3 kg and the cost is $193

.

Table 5- BOM Cradle Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 23 3.3. Tank Sub-Subsystem

The CNG tank used on Silverado is a type 3 container made by Structural Composite Industries, a Worthington Cylinders Company as shown in Figure 8 . CNG cylinders are available in 4 types, with type 1 being the heaviest and least expensive to type 4 being the lightest and most expensive. Type 3 tanks have a seamless and gas tight metal liner reinforced by composite wrap around the entire tank. The tank has a 15 year service life after which the tank must be replaced. Type 3 CNG tanks are pressure rated for 3600psi and are tested at 5500psi. Worthington manufactures all thei r cylinders to aviation standards, with a burst safety factor of at least 3.0 and with design

verificat ion impact testing about the full cylinder periphery.

Figure 8- CNG Tank

(Source: FEV, Inc. photos) 

### 98kg / 216lbsAnalysis Report BAV-P310324- 03 June 26, 2015 Page 24

Figure 9- CNG Tank Label

(Source: FEV, Inc. photos)

Figure 9 show the label Figure 10 show the Silverado CNG Tank sectioned lengthwise. Composite wrap thickness thins around the radius and thickens around the ends of the

tank.

Figure 10 - Silverado CNG Tank Section # 1

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 25

Figure 11 - Silverado CNG Tank Section # 2

(Source: FEV, Inc. photos)

Steps and images for CNG tank manufacturing are outlined below:

Step 1: Saw seamless aluminum tube

Step 2: Ultrasonic scanning of tube for imperfections

Step 3: Preheat tube to initiate forming

Step 4: Spin forming

Step 5: Stress relief

Step 6: Machine neck threads

Step 7: Apply c orrosion protectant

Step 8: Composite carbon fiber wrap

Step 9: Resin coating

Step 10: Oven c ure resin

Step 11: Hydrostatic leak test

Step 12: Random sample burst test

http://www.youtube.com/watch?v=XxRiyCGtKgoAnalysis Report BAV-P310324- 03 June 26, 2015 Page 26

Figure 12 - Step 1: Seamless Aluminum Tube Cut to Length

http://www.youtube.com/watch?v=-NDvGYfwTxs

Figure 13 - Step 3: Preheating of Blank Prior to Spin Form

http://www.youtube.com/watch?v=XxRiyCGtKgoAnalysis Report BAV-P310324- 03 June 26, 2015 Page 27

Figure 14 - Step 4 : Blank Chucked in Spin Form Machine

http://www.youtube.com/watch?v=-NDvGYfwTxs

Figure 15 - Step 4-1 : Spin Forming

http://www.youtube.com/watch?v=-NDvGYfwTxsAnalysis Report BAV-P310324- 03 June 26, 2015 Page 28

Figure 16 - Step 4-2 : Spin Forming

http://www.youtube.com/watch?v=-NDvGYfwTxs

Figure 17 - Step 5: Heat Treatment (Stress Relief)

http://www.youtube.com/watch?v=XxRiyCGtKgoAnalysis Report BAV-P310324- 03 June 26, 2015 Page 29

Figure 18 - Step 8: Carbon Fiber Wrapping

http://www.youtube.com/watch?v=XxRiyCGtKgo

Figure 19 - Step 8: Carbon Fiber Wrapping (Continued)

http://www.fleetsandfuels.com/fuels/cng/2012/11/cleanng-readies-all- new -cngtank/attachment/cleanng_magmacel-1111Analysis Report BAV-P310324- 03 June 26, 2015 Page 30
The bill of materials for the CNG Tank is shown in Table 6

. Tank mass is 98 kg and the cost is $1,073.

Table 6- BOM CNG Tank Sub-Subsystem



### 4. Safety Devices Subsystem

4.1. High Pressure Lock-Off Valve Sub-Subsystem

Figure 20 shows the High Pressure Lock-Off Valve directly connected to the driver’s

side tank end. All components included in this Sub-Subsystem are shown in Figure 21

. The protective cover and collar were assumed die casting and sand cast respectively for high volume production. The High Pressure Lock-off Valve body was machined from billet aluminum. All components making up the HPLV were identified in the cost file with the BOM part number and the ID number assigned in Figure 22

.Analysis Report BAV-P310324- 03 June 26, 2015 Page 31

Figure 20 - High Pressure Lock-Off Sub-Subsystem – Assembled

(Source: FEV, Inc. photos)

Figure 21 - High Pressure Lock-Off Sub-Subsystem – Components

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 32

Figure 22 - High Pressure Lock-Off – Exploded View

(Source: FEV, Inc. photos)

The bill of materials for the High Pressure Lock-Off Valve Sub-Subsystem is shown in

Table 7

. Ma ss is 3.7 kg and the cost is $55.

Table 7- BOM High Pressure Lock-Off Valve Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 33 4.2. Safety Relief Valve Sub-Subsystem

Figure 23 shows the Safety Relief Valve assembled to the passenger side tank end. Separate outlets are used for both the pressure/temperature relief valve and the burst disc. Both outlets join the ma nual purge valve outlet before continuing to the underbody atmospheric vent.

Figure 23 - Safety Relief Valve – Assembled

(Source: FEV, Inc. photos)

Figure 24 identifies all components included in the Safety Relief Valve Sub-Subsystem. Unlike the protective collars of the HPLV, cross sectional thickness of the safety relief valve protective collars were able to be die cast. The protective cover was estimated as die cast as well. With exception to seals, washers, and fasteners, core components are

all made from stainless steel and aluminum.Analysis Report BAV-P310324- 03 June 26, 2015 Page 34

Figure 24 - Safety Relief Valve – Components

(Source: FEV, Inc. photos)

Figure 25 shows the components with the pressure relief device. In the left of the picture is the over pressure relief valve assembly with bel le ville spring set and heat sensitive seat. The second component in from the right is the rupture disc.

Figure 25 - Safety Relief Valve – Exploded View

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 35

The bill of materials for the Safety Relief Valve Sub-Subsystem is shown in Table 8

. Mass is 1.0 kg and the cost is $ 26

.

Table 8- BOM Safety Relief Valve Sub-Subsystem

4.3. Excess Flow Valve Sub-Subsystem

Figure 26 shows the Excess Flow Valve Assembled to the High Pressure Lock-Off

Valve.Analysis Report BAV-P310324- 03 June 26, 2015 Page 36

Figure 26 - Excess Flow Valve – Assembled

(Source: FEV, Inc. photos)

Figure 27 shows the internal components comprising the Excess Flow Valve. All working components of this assembly are stainless steel. The spool diameters and faces are finished with grinding. The sealing surface of the mating housing are finished ground as well

. The T-fitting is forged stainless steel.

Figure 27 - Excess Flow Valve – Exploded

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 37

The bill of materials for the Excess Flow Valve Sub-Subsystem is shown in Table 9

. Mass is 0.5 kg and the cost is $23.

Table 9- BOM Excess Flow Valve Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 38 4.4. Purge Sub-Subsystem

Figure 28 shows all components included in the Purge Sub-Subsystem. All fuel lines

are seamless 316 stainless steel. The flex hose is s tainless s teel jacketed PTFE. The T and elbow fittings are forged 316 stainless steel.

Figure 28 - Purge Sub-Subsystem – Components.

(Source: FEV, Inc. photos)

The bill of materials for the Purge Sub-Subsystem is shown in Table 10 . Mass is 1.5 kg and the cost is $47.

Table 10 - BOM Purge Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 39


### 5. High Pressure Circuit Subsystem

5.1. Filler (Refueling ) Sub-Subsystem

Figure 29 shows all the components included in the Filler Sub-Subsystem.

Figure 29 - Filler Sub-Subsystem – Components

(Source: FEV, Inc. photos)

Figure 30 is an exploded view of the fill port (NGV1) mechanism. The body of the fill port is constructed of stainless steel. The mounting cup for the fill port is injection molded plastic.

Figure 30 - Fill Port – Exploded View

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 40

The bill of materials for the Filler (Refueling) Sub-Subsystem is shown in Table 11

. Mass is 0.6 kg and the cost is $21.

Table 11 - BOM Filler (Refueling) Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 41 5.2. Distribution, High Pressure Sub-Subsystem

Figure 31 shows all components included in the Distribution, High Pressure SubSubsystem. All lines are seamless stainless steel (ASTM-213). The elbow and ball valve are stainless steel as well. Bracket costs were estimated using progressive metal stamping for high volume production.

Figure 31 - Distribution, High Pressure Sub-Subsystem

(Source: FEV, Inc. photos)

The bill of materials for the Distribution, High Pressure Sub-Subsystem is shown in

Table 12 . Mass is 2.4 kg and the cost is $64.

Table 12 - BOM Distribution, High Pressure Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 42 5.3. Filter Sub-Subsystem

Figure 32 represents the Filter Sub-Subsystem.

Figure 32 - Filter Sub-Subsystem – Components

(Source: FEV, Inc. photos)

Figure 33 shows an exploded view of the CNG filter. The upper and lower black anodized housings are billet machined; however forging was assumed for high volume production of the pressure vessel. The filter is a ‘coalescing element composed of an epoxy saturated, borosilicate glass microfiber tube surrounded by a coarse fiber drain layer retained by a synthetic fabric safety layer.’ ( www.parker.com ) The O-rings are Buna-N and the plastic filter internal components are Acetal plastic.

Figure 33 - CNG Filter – Exploded View

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 43

The bill of materials for the Filter Sub-Subsystem is shown in Table 13 . Mass is 0.6 kg and the cost is $18.

Table 13 - BOM Filter Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 44

5.4. Pressure Regulator Sub-Subsystem

Figure 34 shows all the components included in the Pressure Regulator SubSubsystem including the bracket, guard, fasteners, regulator, and ground strap.

Figure 34 - Pressure Regulator Sub-Subsystem – Components

(Source: FEV, Inc. photos)

Figure 35 shows an exploded view of the CNG regulator. The unit produced by GFI is a single stage regulator. It features coolant heating, integral high pressure solenoid shut-off, pressure and temperature transmitters. The upper and lower housings are both die cast. A variety of manufacturing processes are used in creating the internals including wire forming, machining, injection molding and stamping. Cost considerations were made for stringent cleanliness requiremen ts needed for this application.

Figure 35 - Pressure Regulator – Exploded View

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 45

The bill of materials for the Pressure Regulator Sub-Subsystem is shown in Table 14

. Mass is 4.1 kg and the cost is $78.

Table 14 - BOM Pressure Regulator Sub-Subsystem



### 6. Low Pressure Circuit Subsystem

6.1. Distribution, Low Pressure Sub-Subsystem

Figure 36 shows all components included in the Low Pressure Distribution SubSubsystem including the brackets used for line mounting. Lines used for CNG transport

are either stainless steel or braided stainless steel reinforced flex lines. Coolant transfer hoses for the pressure regulator heating circuit are SAE20R3 and the regulator vacuum

reference hoses are SAE30R7.Analysis Report BAV-P310324- 03 June 26, 2015 Page 46

Figure 36 - Distribution, Low Pressure Sub-Subsystem – Components

(Source: FEV, Inc. photos)

The bill of materials for the Distribution, Low Pressure Sub-Subsystem is shown in

Table 15 . Mass is 4.6 kg and the cost is $109.

Table 15 - BOM Distribution, Low Pressure Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 47 6.2. Fuel Rails Sub-Subsystem

Figure 37 shows the Fuel Rail Sub-Subsystem partially disassembled. The fuel injector has been removed from the assembly to be included in its own sub-system. The wide upper rail shown in the top center of the image supplies the fuel injector. The lower rail shown center right of image is a shorter rail that is fed from the injector. The CNG flow path then travels through a barbed fitting to a rubber hose and finally to an intake

manifold mounted nozzle shown in Figure 38 . The nozzle is a straight thru diameter with no specialized geometry.

Figure 37 - Fuel Rails Sub-Subsystem – Components

(Source: FEV, Inc. photos)

Figure 38 - Injector Nozzle – Components

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 48

The bill of materials for the Fuel Rail Sub-Subsystem is shown i n Table 16 . Mass is 3.8 kg and the cost is $74.

Table 16 - BOM Fuel Rails Sub-Subsystem

6.3. Fuel Injector Sub-Subsystem

Figure 39 shows all components included in the Fuel Injector Sub-Subsystem. On e (1) CNG injector is used for each cylinder.

Figure 39 - Fuel Injector Sub-Subsystem – Components

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 49
CNG rail pressure is 90

- 110 psig. In comparison, gasoline fuel injector rail pressure is approximately 55 psig. Lower energy density of CNG requires a higher flow rate. The construction of the CNG injector is very similar to a gasoline injector with a cost premium for non-lubricated fuel operation

. Figure 40 shows a cross section of the CNG injector.

Figure 40 - CNG Fuel Injector – Sectioned

(Source: FEV, Inc. photos)

The bill of materials for the Fuel Injectors Sub-Subsystem is shown in Table 17 . Mass is 0.2 kg and the cost is $95.

Table 17 - BOM Fuel Injectors Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 50


### 7. Controls Subsystem

7.1. Control Module Sub-Subsystem

All components associated with the Control Module Sub-Subsystem are identified in Figure 41 . From left to right are the ECU mounting bracket, ECU, Intake Air Temperature module and Fuel Pump module. The Silverado CNG system utilizes a separate ECU.

Figure 41 - Control Module Sub-Subsystem – Components

(Source: FEV, Inc. photos)

Figure 42 shows the interior of the CNG ECU including both die cast covers, seal,

board and fasteners.

Figure 42 - CNG ECU – Exploded View

(Source: FEV, Inc. photos)

ECU circuitry was reviewed in detail. Each board component was identified and costed individually incl uding assembly cost. Figure 43 and Figure 44 show top and bottom views of ECU board with number labels matching the table with circuit description.Analysis Report BAV-P310324- 03 June 26, 2015 Page 51

Figure 43 - CNG ECU Board with Circuit ID numbers – Top

(Source: FEV, Inc. photos)Analysis Report BAV-P310324- 03 June 26, 2015 Page 52

Figure 44 - CNG ECU Board with Circuit ID numbers – Bottom

(Source: FEV, Inc. photos)

The bill of materials for the Control Module Sub-Subsystem is shown in Table 18 . Mass is 3.7 kg and the cost is $232.

Table 18 - BOM Control Module Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 53 7.2. Wire Harnesses Sub-Subsystem

Figure 45 shows the components comprising the Wire Harness Sub-Subsystem, main harness shown left and rearward harness shown right. Both harnesses are dedicated to the CNG system. The main harness connects the ECU, IAT module, regulator and injectors. The rear harness connects the main harness, fuel pump

, fuel pu mp module, as well as high pressure safety lock off connections.

Figure 45 - Wire Harness Sub-Subsystem

The bill of materials for the Wire Harnesses Sub-Subsystem is shown in Table 19

. Mass is 2.8 kg and the cost is $71.

Table 19 - BOM Wire Harnesses Sub-SubsystemAnalysis Report BAV-P310324- 03 June 26, 2015 Page 54 

### 8. Cost Summary and Conclusion

The primary project objective was to determine net incremental direct manufacturing costs (NIDMC) fo r a complete Compressed Natural Gas (CNG) fuel system. The system selected to represent the light-duty pickup truck segment was a 2013 Chevrolet Silverado equipped with the bi-fuel option. A NIDMC of $2,276 ( 

### Table 20 ) represents the calculated cost to the OEM to add a CNG fuel system to an existing gasoline vehicle. The boundary conditions for the cost analysis included manufacturing in the United States, high production volume, and a mature and competitive market place. Not included in the NIDMC are OEM indirect costs such as corporate overhead, research and develop, and tooling (incremental tooling provide separately in Appendix A). In addition, there is no OEM profit included in the calculation. Both OEM indirect costs and profit are added to the FEV calculated NIDMC using an EPA Indirect Cost Multiplier (ICM). The application of the multiplier was outside the scope of this project.

Table 20 - CNG Subsystem Cost Summary Overvi ew

Subsystem Total Direct

Manufacturing
(i.e., material,

labor and
manufacturing
overhead) Total Markup

Cost (i.e., end

item scrap,
SG&A, Profit, ED&T/R&D) Total

Packaging

Cost Net

Incremental

Direct
Manufacturing

Cost

Storage $1,175 $177 $9 $ 1,360
Safety Devices $126 $ 24 $1 $ 15 1
High Pressure

Circuit $154 $28 $3 $ 184

Low Pressure

Circuit $268 $ 38 $ 2 $ 27 8

Controls $268 $ 35 $1 $ 303

TOTAL $1,959 $302 $15 $2,276

Additional cost details for each subsystem listed in Table 20 can be found in Appendix

A . As highlighted in Figure 46 , t he largest contributor to the overall CNG system cost is the storage system at 60% of the total NIDMC.Analysis Report BAV-P310324- 03 June 26, 2015 Page 55

Figure 46 - CNG Subsystems

Material cost makes up $1531.20 of the total $2276.20 for the CNG system, most of which comes from the carbon-fiber wrapped fuel tank. See Figure 47 for a detailed

breakdown.

Figure 47 - Manufacturing and Mark-up Cost

All costs were developed using a volume assumption of 450,000 units per year. This cost analysis is inclusive of all associated assembly cost from component to vehicle. Calculations were performed to determine equipment sizing, cycle times and material usage requirements. FEV utilized its extensive database of rates for equipment, labor,Analysis Report BAV-P310324- 03 June 26, 2015 Page 56 material, end item scrap, selling, general and administrative (SG&A ), profit, and engineering, design and testing (ED&T) to develop costs representative of what an OEM would incur for such a system in high volume automotive manufacturing.

Costs were developed for all critical components by detailing each operation in a Manufacturing Assumptions Quote Sheet (MAQS). Process calculators were used to determine equipment size and corresponding rate ($/hr), cycle time (seconds) and material usage (kg). For example, the Pressure Regulator Cap was identified as an aluminum die casting. The number of slide pulls, cavities, part width, part height, average wall thickness, parting line area, cavity surface area, and max wall thickness were all used to determine the die-casting machine size, cycle time and material usage. This information was then transferred to the MAQS where rates are pulled in for material, labor, manufacturing overhead/burden, end item scrap, SG&A, profit, and

ED&T. Cost contributions are then calculated for these core cost elements. Similar process calculators are used for subsequent processing such as machining, where all machine features are measured, speed and feed rates assigned based on the respective material, and feed times calculated. In addition pallet changes, tool changes, rapid times, as well as est im ated work pieces per fixture are used to estimate the total cycle time. Finally all processes are summed, end item packaging estimated, and total

cost calculated. Cost contributions for the core cost elements are then linked to the Cost Model Analysis Template (CMAT). The CMAT incorporates cost data from various Sub-Subsystems into one summary sheet. For detailed cost breakdown, see Appendix

A

. Overall system costing methods are either calculated or commodity. All fastening hardware (bolts, washers, nuts, etc...) come from online bolt manufacturer’s pricing. Commodity pricing was also used on small components within larger assemblies such as the ECU circuits and components within assemblies like the pressure regulator. For example commodity pricing was referenced to estimate costs for components like springs, seals, solenoids, and diaphragms.Report FEV-P310324- 03 June 26, 2015 Page 57



### 9. A ppendix A

The CNG system level cost summary, by major components and assemblies, is shown below in Table 21

.
Table 21 - Complete Cost Summary (CMAT) – CNG System