is shelf life a safety consideration? · 2018. 4. 1. · from my experience, if products are used...

IS SHELF LIFE A SAFETY CONSIDERATION?A Case History Related to Recent TCP Incidents

AUTHOR: KERRY DALY

APPS‐19‐18

What is Shelf life?

Shelf Life to the Industry

Application for TCP

Timeline for Recent Incidents

Post job Analysis

Corrective Actions

Conclusion

Questions

INDEX

Is Shelf Life a Safety Consideration? A Case History Related to Recent TCP IncidentsAPPS‐19‐18

The period of time during which explosives may be stored and remain suitable for use (i.e. function at original performance levels within a few percent).

Five (5) years is the typical length, however this is determined solely by the manufacturer and assumes storage in original packaging and under dry, well ventilated conditions.

WHAT IS SHELF LIFE?


Controversial because it assumes:

Some level of warranty

• replacement or monetary compensation if it does not function at original performance levels

May carry legal implications

• in many cases the product cannot be used beyond the stated time if under contractual terms.

Manufacturers prefer to limit the time to reduce their responsibility,

Purchasers (service companies in particular) desire longer times in order to maximize the use.

Operators, in many contracts, will reduce the shelf life even more

• (maximum 1‐2 years) in an effort to ensure explosive product performance.

SHELF LIFE TO THE INDUSTRY


Service companies may or may not manufacture their own explosives.

In the case of TCP detonators (percussion primers, percussion initiators, and pyrotechnic time delays),

• Many are manufactured by only a few companies and then commonly used by the industry.

For this study, this is the case regarding the explosives used in the Top Dual firing head (a design common to the industry), which combines:

1. A pressure‐activated time delay firing head.

2. A drop bar safety mechanical firing head

The purpose is to provide a level of redundancy (but not truly) for safety purposes.

APPLICATION FOR TCP

2.

1. Discreet firing systems connect to common explosive train at top of gun


Regarding redundancy:

• Some operators do not allow TCP firing heads to be run at top and bottom of guns, due to historical concerns.

• Thus the reason for running the Top Dual FH, as it offers a second chance in case of problems

• As stated previously, this is not truly redundant, as the dual FH connects to the single explosive train.

• In cases where Operators allow top Safety Mechanical or Pressure FH actuation, as well as bottom Pressure FH actuation, this does provide truly redundant system.

• Per the new API RP67 (now out for ballot), there is nothing that disallows top and bottom firing, so long as the design has been demonstrated as safe and all parties agree.

APPLICATION FOR TCP

.


Pyrotechnic time delays began failing (ultimately the root cause).

• Long, successful history of use

• Stored properly

• Still within the shelf life limit

Per Job Design using Top Dual FH,

The first option to fire was by pressure activation,

but when the time delay low‐ordered it blew down (destroyed) the single booster in the top gun

this rendered the entire gun string inoperable (unbeknownst at the time)

TIMELINE FOR RECENT INCIDENTS

XX

X

1.


Contingency plan in case of no‐fire,

Activate the backup, so a bar was dropped to impact the Safety Mechanical FH

However guns failed to fire since the top booster was already destroyed.

Exacerbating the issue, attempts to fish the drop bar were unsuccessful

This resulting in a High‐Potential Risk Operation

Required pulling the live guns with drop bar still present

TIMELINE FOR RECENT INCIDENTS2.

X

√


Because of well‐orchestrated operations based on strict safety protocols

Established by the Service Company

Well Orchestrated by the Operator and Service Company

The recovery was successful with no safety incident.

TIMELINE FOR RECENT INCIDENTS


1. Blow‐down was found in the top gun

2. Time delay had low‐order output, which destroyed the boostered detonating cord transfer lines

3. X‐rays were inconclusive as to where the time delay failed

POST ANALYSIS

X

2.

1.

XX


CORRECTIVE ACTION Because this lot of time delays was from one manufacturing run from the supplier

No other lots available and supplier was no longer making this product

Decision was to change time delay supplier

Since April 2017, over 75 TCP jobs have been completed with no misfires or NPT recorded

2.

1.


CONCLUSION As related to Shelf Life, the time delays were within the 5‐

year limit as established by the supplier

They had long successful history of use with no related incidents

They were stored in original packaging, were kept dry, and had vapor barriers sealed

Unfortunately, at about 4‐year mark, the time delays started to fail

This was not one delay, but several, with a reduced success rate of ~50% firing

At this point we do not know what changed

However when we stopped using them, our success rate went back to 100%


CONCLUSION Had we limited the Shelf Life to 3 years, we would not have

experienced a Hi‐Po Incident

So I pose the question for debate‐

Is Shelf Life a Safety Consideration?

My opinion is that this is manufacturing defect that took several years to manifest

This is an isolated supplier problem, not an industry one.

From my experience, if products are used within the Shelf Life as stated by the manufacturer, then success rates remain as high as when originally manufactured.

So, it is a Safety Consideration, but the manufacturer who is warrantying the product knows best!


QUESTIONS? THANK YOU!

APPS‐19‐18AUTHOR: KERRY DALY

is shelf life a safety consideration? · 2018. 4. 1. · from my experience, if products are used...

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