Safety of Test Processes in Contract NR006357-6.17

Deep Life Ltd. Non-confidential

Safety of Test Processes in Contract NR006357-6.17.2

DOCUMENT NUMBER:[Filename]

Safety Test Processes_060821.doc

ORIGINATOR: Dr. Alex Deas, Alexei Bogatchov, Dr. Vladimir Komarov

DEPARTMENT: QA and HSE

DATE ORIGINATED: 21st August 2006

REVISION: A

APPROVALS

ME________________________________Hardware Architect

__________________________Date

SM_______________________________Software Architect

__________________________Date

AB________________________________Project Manager

__________________________Date

VK______________________________

Quality Officer

__________________________Date

Controlled Document Classified Document DO NOT COPY.

Revision History

Revision Date Description

A 21st August 2006 Report of Review

Copyright 2006 Deep Life Ltd

All information and data provided herein is for general information purposes only and are subject to change without notice or obligations. All trademarks and design marks are

acknowledged to be the property of their registered owners.

Safety Test Processes_060821.doc Rev. A 1 of 9

This document is the property of Deep Life Ltd. Circulation is not restricted.


Table of Contents

1 SCOPE ..................................................................................................................... 3

2 PURPOSE ................................................................................................................ 3

3 PROCESSES SUBJECT TO SPECIAL SAFETY MONITORING ............................ 3

3.1 Gases and Chemicals ........................................................................................................................................... 3

3.2 Moving Machinery ............................................................................................................................................... 3

3.3 Manned Testing .................................................................................................................................................... 3

3.4 Pressure Chambers .............................................................................................................................................. 4

3.5 Risk Review .......................................................................................................................................................... 5

4 SUMMARY OF TEST PROCESSES ........................................................................ 5

5 VERIFICATION OF EDA PREDICTED FAILURE POINTS ..................................... 6

6 CONCLUSIONS AND RECOMMENDATIONS ........................................................ 9




1 SCOPE

This document covers tests proposed under contract NR006357-6.17.2: a commercial rebreather project for manned dive operations to 600m.

2 PURPOSE

The purpose of this review is to ensure the test processes themselves do not present a significant safety hazard. This review is in accord with Deep Life Quality Procedure QP-22 (Risk Assessment).

The reason for this review is the depths the equipment under design is tested to, of 1400msw, involves considerably greater pressure and stored energy than the 200msw depths used to date for rebreather testing.

3 PROCESSES SUBJECT TO SPECIAL SAFETY MONITORING

3.1 Gases and Chemicals

The project uses high pressure non-breathable gas such as compressed helium, carbon dioxide, carbon monoxide, methane and high pressure oxygen.

Staff using these gases are trained in their use. The engineer directing each trial has a formal qualification as an advanced gas blender and oxygen technician.

Amounts of gas stored on the premises are kept to the minimum needed for the test. This means cylinders are ordered for the test, with size and contents required for that test. After the series of tests, the cylinders are removed from the premises. Cylinders of poisonous gases are kept outside (carbon monoxide, methane).

The room where gases are stored and used is sufficiently large and has adequate direct external ventillation, to prevent any discharge from reducing the atmosphere in the room to below that needed to sustain life.

3.2 Moving Machinery

The only moving machinery used by the tests is the breathing machines. These do not present any safety hazard, on the basis that:

1. The drive power is limited so there is no risk of injury from the moving parts

2. There are no pinch risks, or risks of any cutting action

3. They operate from 24V DC, insulated, and are earthed, so there are no electrical risks

4. The noise limits are under that requiring ear defenders

5. For most of the tests the machines operate in a test chamber which can contain any event the machine is capable of producing from failing components (300mm dia and 600mm dia chambers).

3.3 Manned Testing

Manned testing will be carried out only when the unit has passed all other tests and shown to comply with EN14143:2003, NORSOK-U101 and EN61508.




A separate PPO2 monitor will be used for all manned tests. These comprise three O2 sensors in a kidney fitting into a P Port, driving simple and independent displays, in the same manner as the KISS rebreather.

All manned testing will comply with HSE guidelines, including the presence of safety divers and standby divers. Ample Open Circuit bail out will be available at all times. Initial testing will be in a protected environment, namely a pressure chamber certified for manned use.

These measures appear adequate for the manned tests.

3.4 Pressure Chambers

A large number of tests involve pressure chambers, all but one of which is located at Deep Life's premises and were designed by Deep Life.

These pressure chambers are as follows:

Equipment Serial # Internal Dimension

Materials Max Operating

Depth

Hydraulic Test Pressure

Component He Susceptibility Pot

DLC_A39 125mm x 20mm

SS 316 6000msw 800 bar

Component Pressure Pot

DLC_A40 125mm x 20mm

SS 316 6000msw 800 bar

Oxygen Chamber DLC_A50 125mm x 58mm

Nickel-Bronze 6000msw 800 bar

Handset Test Chamber DLC_A10 160mm x 300mm

Nickel plated Al, with 160mm diameter 40mm thick Acrylic viewing window protected by external 7mm SS 316 ring.

200msw 40 bar

Scrubber Test Chamber DLC_B05 300mm x 600mm

High Carbon Steel, Plated

1400msw 300 bar

System Chamber DLC_B20 600mm x 1000mm

High Carbon Steel Rings, SS 316 liner, Plated. Remote control

1400msw 300 bar

OBS Chamber OBS 500m 1.2m x 0.5m Carbon steel, painted

500msw 100 bar

The System Chamber is not ready at the time of this report: it is in manufacture. The System Chamber has been designed specifically to avoid gross failure by using a ring construction, preventing any failure propagating more than 20mm. All other vessels are CNC machined from solid blanks, or in the case of the OBS Chamber, cast.

The design procedure in Deep Life for pressure vessels is to obtain and comply with the National standard for pressure vessel design and certification, for the country in which the chamber will be used, with a minimum standard of:

1. Full 3D stress analysis using EDA tools, at double the operating pressure, and with materials downrated by 15%.




2. All threads to be at least as strong as those in European specifications for pressure vessel threads. Where a non-standard diameter is required, the thread for the next diameter up is used for teeth size, pitch and length of thread.

3. All removable caps or sections cause the gas seal to be lost while there is sufficient thread to comply with the full test pressure strain on the section. This prevents sections flying off or moving rapidly, if openned when the chamber is under pressure.

4. Construction of the chamber, with verification that the correct material has been used.

5. Annual hydraulic pressure testing of the chamber to twice the operating pressure. All chambers are tested after manufacture and in the August of each year.

6. Visual inspection of the chamber, particularly stress points identified in the original stress analysis, using magnification.

3.5 Risk Review

A Risk Review has been carried out of the proposed test processes, the results of which are:

1. The design process for the chambers relies heavily on EDA tools. The tools have been verified for pressures to 200 bar by applying the test pressure twice the operating pressure and checking that the part returns to its original size. No real analysis has been done for higher pressures.

This is perceived to be a risk: materials may be damaged by hydraulic testing, without stress marks being visible, then fail subsequently at a lower pressure. This risk is particularly true of plastic parts, which do not have such a linear strain-extension curve as for metals. The Risk Review concluded an action to take to verify the EDA tools again by testing to destruction the largest plastic component used in the tests, and compare the failure to that predicted. This test and its results are reported later in this document.

The EDA tools are used to design the part with as little margin/waste as possible. This means the part is analysed with 15% downgrading of material only. For example, a plastic window that is designed for use at 200msw, will be designed to fall outside the yield point of the material at 430msw (Operating pressure x 2 + 15%) for the worst case material of the specified type.

2. O2 compatibility testing should continue to be performed on an open site behind a blast wall. It must not be performed in a laboratory or other closed space, due to the fire risk.

3. Some metal parts are washed in benzene before delivery to Deep Life. All parts to be washed again in a solvent that does not leave residue, then with soap and hot water, to remove any hydrocarbon residues.

4. The colour of O rings should be changed: some black Viton is used, which is indistinguishable from other O ring materials.

4 SUMMARY OF TEST PROCESSES

The project requires tests to verify compliance with EN14143:2003 extended to 600m, and with additional tests to meet NORSOK U101 for depths to 600m. All components are additionally tested to 1400msw for helium susceptibility, and to 1200msw for vessels not at ambient.

Specific test plans exist for O2 injectors, rebreather testing and testing of assisted breathing apparatus.

Formal verification of all designs has been carried out prior to the start of testing, so their potential behaviour is understood.




5 VERIFICATION OF EDA PREDICTED FAILURE POINTS

The original stress analysis for the view port on the Handset Test Chamber is the largest plastic component involved in the tests. The present port is fabricated from Acrylic, and protected from edge fragmentation by a Stainless Steel ring, as shown in the figure below. A port was selected for destructive testing to verify the safety reliance that can be placed on EDA predicted failure points.

Fig 1: The Acrylic View port design, showing SS protection ring and fixing. Material is 40mm thick clear acrylic, diameter of port inside the viewing area is 160mm, overall diameter is 205mm.

Fig 2: Original Strain Analysis of 160mm View Port at 40 bar pressure




Fig 3: Secondary Strain Analysis of 160mm View Port at 40 bar pressure with removal of sharp corner: recognised as the primary failure point.

Fig 4: View Port after destructive testing, with failure completely internal to the material. This occurred at 46 bar: this is almost exactly the pressure and location the design engineer expected (40 bar + 15%).




Fig 5: View from externior face, showing failur from join identified in EDA tools, but completely internal to the material. This failure mode is preferred to that of Polycarbonate (block fragmentation).

Fig 6: Modified design moving failure to interior face by removing the step. This shows failure modes is predominantly from interior stresses, starting at a change in profile.




6 CONCLUSIONS AND RECOMMENDATIONS

1. Overall, the test procedure proposed appears reasonably safe and is within the intended design capabilities for the test systems.

2. No data is available on the OBS chamber. OBS should be invited to provide this prior to pressure tests being carried out.

3. The EDA tools do seem accurate in predicting the failure point of materials, under pressures and in profiles used in the proposed test process for the contract under consideration. The EDA tools seem remarkably accurate in predicting the failure point, when used appropriately, even for plastics.

4. The test confirmed the tight tolerance the design engineers are achieving in avoiding excess material. This means it is important not to over-pressurise vessels during hydraulic testing.

5. Recommendation: Eddy Current testing should be applied to all metal parts after all hydraulic tests to ensure no internal failure has occurred. All plastic parts should be clear and be inspected visually. The destructive test that forms this study shows such hidden failures do occur and if not detected, would constitute a safety risk. This applies to all parts subject to hydraulic testing.

6. No other safety hazards were picked up during the review that suggest any other change in processes.



Safety of Test Processes in Contract NR006357-6.17

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