www.randall.co.nz

By Nigel

This is an area where there is a lot of confusion as to what the real requirements are, and the process to get there for existing in-service tanks certified and tested as complying with current requirements.

HSNO Tanks under 60,000 litres fall within the scope of the approved code of practice for the “Management of Existing Stationary Container Systems up to 60,000 litre Capacity”.

The COP allows for existing tanks to be retrospectively certified for compliance to the HSNO Act.  In layman’s terms the COP allows you a means of compliance for existing containment systems. It does not allow you to reuse these containment systems in new installations

Unknown tanks cannot be reused in a process Environment.

The tank and its installation do not have to be bought up to full code compliance immediately, but a plan of action has to be put in place which the HZNO test certifier then refers to.

Tanks with hazardous chemicals have to be judged against formal codes such as API 650, while the other tanks are judged to fitness for purpose criteria.

Fitness for purpose criteria is still about risk management and includes consideration of the  site  installation (includes  wind and earthquake), the minimum required shell thickness and any other factors that are required to be considered to  manage risk- for example access ways.

Tanks with hazardous chemicals – the tank and its installation are assessed for earth quake. The tank construction, its detailing, are assessed for the specific type of chemical that are contained within the tank. Typical things that may be checked out and considered, include tank venting, tank over flow, tank welds, weld location, tank penetrations, shell thickness, hold down bolt size,  type of tank foot print, foundation mass  and  secondary containment systems.

Secondary containment – it’s not just about the size of the secondary containment but also its relative shape with respect to the height of the tank, drainage, and the type of chemicals the secondary container systems are expected to contain.

The process involves:

1. Contact your local HZNO test certifier- such as Tony Neilson at EnviroHaz Ltd,
2. Your test certifier will advise as to what additional engineering information is required.
3. We liaise with the test certifier to confirm requirement
4. We inspect, check, calculate the tanks to codes as required and determine what is required to bring the tank installation up to specifications
5. We work with you to determine a realistic upgrade schedule to bring the tanks to full COP requirement
6. We issue a statement of design compliance including a schedule of work (if required) including  design life and minimum shell thickness
7. The test certifier on acceptance and verification of the information, and that all of the other requirements that he has set are met, will issue you with a test certificate and data label (if required)

Call us on 0800 762 763 for all enquiry on the compliance of existing tank installations

Nigel Randall Client Services Manager,

Randall’s

Visit us at www.randall.co.nz for more details

Or at 8 Matipo Lane, Palmerston North.

Randall report #3 2012

The second month has all but gone and we are now into the serious work of adding value to clients’ work.  I truly enjoy going around manufacturing workshops, taking an avid interest in what is being done – because it is what I do.

I think about many things, such as the aesthetics of the design, design functionality, design simplicity, design weight, the manufacturing and assembly process, design functionality, design safety, design durability, and maintenance.  I think about how these aspects can be improved by rational thinking. The advantage that I have is that I am often seeing things for a “first time” and therefore question to myself why things are the way that they are. I find that frequently design is based on knowledge that has become out of date, and is now not the best choice, or has become irrelevant.

Employing a Professional advisor can be more than simply – does it meet the code? And should be more than – does it meet the code? It should be about being able to offer good advice in the continuous improvement of products that you make. In doing that, I can add true tangible benefit to the product that you make. Good design is obvious, great design is transparent.

Call me first on 0800 762 763 and we can work with you to redefine your engineering solutions.

Nigel Randall
Client Services Manager, Randalls
Visit us at www.randall.co.nz for more details

Randall report #2 2012

The first month has gone and we are into February- the real work is about to begin for a prosperous and exciting 2012

In 2011 we significantly upgraded our skills in being able to efficiently assess and design tanks – water tanks,wine tanks, chemical tanks, diesel tanks, etc, to site specific conditions as specified by the building code, to earthquake performance standards and to API650. API650 is over 400 pages on its own!

We put in excess of 200 hours in developing a spreadsheet to cover most vertical round ground-based steel tank scenarios without having to use computer stress analysis. For other tanks we use computer stress analysis to quickly calculate the modal response of the tank and its support structure in an earthquake. The use of this technology is not cheap but the results are quick and accurate, and allow us to check or specify plate thickness and tank support. We can also specify welds, weld locations, venting, nozzle location and schedules, annular ring size hold down bolt size and pattern.

The seismic effect on tanks really surprised me. The design effect to visualise is the same as a fly fishing rod, you flick the rod and the fly comes back at once. But as the fly comes forwards you have two loads – with a time delay the rod has changed direction, and the fly is changing direction. Effectively you have a double load one applied from inertia (the change in direction of the fishing rod) and the other the impulsive load from fly. Same effect in a tank filled with liquid. The taller and slimmer the tank, the greater the effect, and numbers are large. For example a 500m3 tank, depending on what is in the tank, the contents can weigh anywhere between 400t to 800t. In an earthquake event, controlling that amount of inertia – say 6m up, and an impulsive load – say 9m up, is a big ask. Hence you need large hold down bolts and an awful lot of them.

We appreciate the importance of good design when the situation becomes critical.

Call us on 0800 762 763 for urgent attention where tanks matter.

Nigel Randall, Client Services Manager, Randall’s your Design Experts
Visit us at www.randall.co.nz for more details

2011 has been  a challenging year on all levels, we tackled interesting projects, we learnt new skills, we became leaner, and  we asked our clients what they wanted from us.

The answer about what our clients really wanted surprised us and that was, they wanted someone with the ability to be able to solve complex or difficult engineering problems quickly.

Made For Very Small logs!!

We learnt about sustainable business and engineering practice which also surprised us . We learnt that making good technical decisions based on sustainability practice almost always results in a cost saving. For example, steel is one of the most sustainable materials on the planet.  As an exercise we examined a logging trailer on the basis that after welding all of the trailer is stress relieved. We set stress criteria and flexibility criteria- we reduced flange thickness but  increased web depth to balance stiffness. It was juggling project but in the end we saved a massive 400kg in weight with no anticipated reduction in service life. That’s 400kg less to buy, less to handle, less process into something useful- and 400kg more in payload. Steel is a wonder material.    At at the end of the year, after 12 months study, we were awarded a Certificate in Sustainable Practice through the Otago Polytechnic.

Call us on 0800 762 763 for urgent attention, where  time lost on complex matters is lost opportunity

Nigel Randall, Client Services Manager,

Randall’s your Design Experts

Visit us at www.randall.co.nz for more details

INTRODUCTION:

The New Zealand Heavy Engineering Research Association (HERA) recently ran a series of seminars, introducing the upcoming move to AS/NZS2980 Qualification of welders for fusion welding of steels.

These very cursory notes are as a result of HERA’s seminar in Palmerston North, and many thanks are extended to Alan McClintock and Mikail Karpenko for their presentation.

SUMMARY:

NZS4711 and 4703 are being phased out, to be replaced by AS/NZS2980. This avoids the cost of updating the rather out-of-date 4711, and remedies the issue of having 2 standards covering a similar area.

AS/NZS2980 is also more useful, in that it covers a wide range of steel types (including high strength and stainless), material thicknesses and more welding processes.

NZS4703, covering stainless steel pipes for the dairy industry, has been incorporated into AS/NZS2980.

Existing NZS4711 and 4703 qualifications remain valid till their expiry date, then to be replaced with qualifications to AS/NZS2980.

New or renewal qualifications to NZS4711 will not be available from 01 April 2011.

Certifying officers will not be re-approved to NZS4711 after 31 March 2011.

MAIN ASPECTS OF AS/NZS2980:

The welder is to follow a qualified Welding Procedure Specification, defining variables such as type and position of weld, weld details, material group and dimensions, consumables, welding machine settings.

A more difficult position qualifies the welder for all joints considered easier to weld. For example, an overhead butt weld in plate qualifies for all plate positions except vertical down.

Weld qualification for welds at a particular material thickness qualifies that weld for a range of thicknesses. For example, material thickness “t” of less than 3mm qualifies for a thickness range of “t” to “2t”.

A weld in a particular material group qualifies that weld for a range of groups. For example, welds in quenched and tempered steels qualifies for that group along with carbon steel below 450MPa yield, fine-grain and cast steels, some nickel alloy steels and low-carbon steels.

Welder test certificate is for 2 years, subject to 6-monthly confirmation by that person’s welding supervisor that the welder has been working within the range of qualification. That welding supervisor would be a designated and responsible employee of the welder’s employer.

The certificate can be prolonged by the examining body for a further 2 years, provided that evidence can be provided of successful weld test or examination of 2 welds in the previous 6 months. The weld test exercise itself does not have to be re-done.

A self-employed welder should engage a supervisor at an independent examining body.

I was asked recently about the legality of a 3-axle simple trailer, versus the more usual 2-axle model. These 2-axle trailers are really useful, but are limited to carrying about a 15 tonne digger. Surely, a 3-axle model could carry an 18 tonne machine?

A simple trailer is like an over-grown car trailer, with a tandem axle set in the middle, and a rigid drawbar that transfers weight onto the towing vehicle’s coupling – usually around 4 tonne.

The gross weight for that tandem axle set is usually 14.5 tonne, as the axles are usually less than 1.3 metres apart. A 3-axle set is permitted to run at 18 tonne.

Clause 4.3(6) of the Dimensions and Mass Rule 41001 specifically limits the Gross Combination Mass for a truck and simple trailer to 32 tonne.

Sections 4.4 of that same Rule specifies that the Trailer : Truck Mass Ratio for combination vehicles shall be 1.5:1 or less – that is, the gross mass of the trailer must not exceed 1.5 times the gross mass of the towing vehicle.

That’s pretty straight forward for, as an example, a rigid truck towing a full trailer – the 1.5:1 ratio sets the maximum trailer weight at 60% of the combination, so if we are running at 44 tonne gross combination mass, the trailer is limited to 26.4 tonne.

This is where I should have checked my logic a little more closely, because my first thoughts for the simple trailer application went something like:

Maximum Combination Mass = 32 tonne

Trailer : Truck Mass ratio = 1.5:1

so maximum gross weight of trailer = 32 tonne x 60%

= 19.2 tonne

typical trailer Gross Vehicle Mass = 14.5 tonne on wheels plus

4 tonne on coupling

= 18.5 tonne

Conclusion: Not much point in having a 3-axle simple trailer, because you can’t utilise the full 18 tonne permitted for a 3-axle set.

Wrong.

Read the words and definition of terms more closely – Clause 4.4 refers to “gross mass”, which is defined as “…the mass of that vehicle and its load…which may be determined by adding the mass on the vehicle’s axles or axle sets.”

Note the subtle difference between these words and the definition for “Gross Vehicle Mass”, which is “…the gross vehicle mass specified…by the manufacturer…”

The 2-axle simple trailer mentioned above would have a manufacturer’s Gross Vehicle Mass of 18.5 tonne – that is, you can load it up to 18.5 tonne total – that is, 14.5 tonne on the wheels and 4 tonne on the coupling – and everyone is happy.

From the Trailer : Truck Mass Ratio aspect, however, things are slightly different.

The Mass Ratio considers the trailer’s “gross weight”, being the sum of the weights on its axles or axle sets – in this case, only 1 axle set, running at 14.5 tonne.

Therefore, for a combination mass of 32 tonne, the truck can run at 32-14.5 = 17.5 tonne, giving a mass ratio of 0.83:1 – well below the permitted maximum.

So, if we consider a 3-axle simple trailer with 18 tonne on its wheels, the truck can weigh 32-18 = 14 tonne, giving a mass ratio of 1.29:1, still below the maximum.

Our 3-axle trailer would have a tare weight of around 4.0 tonne, so the laden weights would be something like:

Mass on axles = 18.0 tonne

plus mass on coupling = 4.0 tonne

less tare weight = 4.0 tonne

gives a payload = 18.0 tonne

Conclusion: Yes, you may carry an 18 tonne machine on your 3-axle simple trailer.

Subsequent note to self: Read those words more carefully.

From the list of impending rule changes coming from the New Zealand Transport Agency, the long-talked about 50 tonne combination mass legislation is expected to be introduced late 2009.

This increased mass limit is touted as being for “high productivity vehicles”.

I wondered what effect this increase might have on the Road User Charges that applicable vehicles would incur, on the basis that no alterations are envisaged to the Dimensions and Mass Rule other than the maximum permitted combination mass – that is, axle and group ratings continue unchanged.

This effectively means that the only rigs that may run at 50 tonne are:

3-axle rigid truck and 4-axle full trailer

4-axle rigid truck and 4-axle full trailer

3-axle tractor unit and 5-axle B-train

The other combinations – including a 4-axle tractor unit with quad semi trailer – are ruled out as axle group ratings will be exceeded.

Using the estimated weights in the following tables and the current Road User Charges, the calculations for each combination of RUC cost per tonne payload show an interesting trend – every one of them gives an increased RUC cost per tonne, of 16-21%.

So much for “high productivity”!

What this tells us is that there will have to be rather more changes than just the Gross Combination Mass – the Road User Charge scale of fees, for one!

Example 1 – 3 axle truck, 4 axle full trailer

44 tonne GCM Truck Trailer Combination

Tare (tonne) 9.0 6.5 14.0

Payload (tonne) 12.0 16.5 30.0

Gross (tonne) 21.0 23.0 44.0

RUC $369.93 $184.80 $554.73

$ / tonne Payload $19.46

50 tonne GCM Truck Trailer Combination

Tare 9.0 6.5 15.5

Payload 13.0 23.0 34.5

Gross 22.0 28.0 50.0

RUC $432.14 $349.47 $781.61

$ / tonne Payload $22.66 (+16%)

Example 2 – 4 axle truck, 4 axle full trailer

44 tonne GCM Truck Trailer Combination

Tare 10.5 6.5 17.0

Payload 11.5 15.5 27.0

Gross 22.0 22.0 44.0

RUC $237.00 $162.42 $399.42

$ / tonne Payload $14.79

50 tonne GCM Truck Trailer Combination

Tare 10.5 6.5 17.0

Payload 14.5 18.5 33.0

Gross 25.0 25.0 50.0

RUC $348.71 $240.25 $588.96

$ / tonne Payload $17.85 (+21%)

Example 3 – 3 axle tractor, 5 axle B-train

44 tonne GCM Tractor 1^st Trailer 2^nd Trailer Combination

Tare 8.0 5.5 5.0 18.5

Payload 9.0 9.5 7.0 25.5

Gross 17.0 15.0 12.0 44.0

RUC $192.99 $93.23 $103.09 $389.31

$ / tonne Payload $15.27

50 tonne GCM Tractor 1^st Trailer 2^nd Trailer Combination

Tare 8.0 5.5 5.0 18.5

Payload 11.0 11.5 9.0 31.5

Gross 19.0 17.0 14.0 50.0

RUC $268.49 $127.22 $172.63 $568.34

$ / tonne Payload $18.04 (+18%)

While this isn’t exactly related to Engineering, it does restore my faith in people, and shows how a few tools that we use all the time at work can actually be very handy!

Last Saturday, I was washing my house’s soffits and guttering, using my Raven Telescopic Water Brush – NZ-made, by Raven Products in Auckland.

I must have been a bit over-zealous with tightening one of the plastic extension collars, because it broke. I had to stop part-way through the job, of course.

After thinking for a little while about the futility of fixing things these days, I decided to be a bit cheeky, and see what happens if I see about getting a replacement.

With my digital camera, I took a photo of the broken part. Next, I used Google to find Raven Products and got their website. I then sent an email to their Technical Services Department, wondering about the possibility of getting a replacement, with the photo as an attachment.

Upon checking my messages on Monday night, behold! a reply from Richard Mitchell, Raven Sales and Marketing Manager, sent that morning and asking me to confirm my postal address so that they could send the piece.

I duly replied, giving my address and confessing that now I’ll have to complete the job. I also asked how I could make payment – might a cheque be acceptable?

Come Tuesday night, another reply from Richard, commiserating with me that cleaning the house is the down-side, but also saying to not worry about payment for this one – one of the perks for buying NZ made.

So, what tools have we used?
- digital camera,
- Internet,
- Google,
- email.

What have we learned?
- these electronic gizmos can be useful,
- buying NZ-made can be good,
- most folk we deal with are great.

The motivation for requiring certification of draw beams and drawbars came from a spate of fatal accidents involving heavy motor vehicles where the drawbars or beams had worn out and the heavy trailer had parted company with the truck. The operators knew when it was time to replace a drawbar or beam because it was then in two pieces

Today is vastly different. Certification costs are in the region of $250-$450 bearing in mind that this certification includes additional components which weren’t around 22 years ago. In real terms certification costs are probable only 25% of what there were then. NZ Transport agency now set the bar.

Do I think things have gone backwards—absolutely?

22 years ago, from a design point of view, things were pretty dreadful—there were some abhorrent designs. A four axle stock trailer with a 100 x 75 rhs pole (had been upgraded from 75 x 75 rhs after it had broken and the trailer had hit the Awatiri. Most drawbeam required upgrading but because we designed to fatigue criteria and as weld has a much lower fatigue allowance than parent metal, the upgraded drawbeam were reminiscent of battleships. Got a lot of ribbing, some good natured, some not so good. After a period of time 5 to 10 years later I thought overall the standard of design and manufacture had improved significantly. Good robust designs made by manufacturers who knew what they were about.

What’s happened now is that we have a whole new generation of designer’s certifiers and regulators. The regulators have added a lot more complexity to the compliance regime in the name of consistency. Many of the new designers have little practical experience about why things are the way they are and rely heavily on the regulators for guidance! They challenge the old heads, saying in not so many words that we are stupid, not realizing that the old heads know full well that this is a numbers game—you can never eliminate the possibility of things going wrong but you can as sure as hell reduce the odds!

The benefit of employing a specialist engineer within your business is, I guess, confidentiality as well as you the business owner or manager being able to call the shots. The dis-benefit is that the cost of employing someone is usually 2.5 to three times their pay (divide that by the number of hours that they are actually doing the job they were paid to do) – they can get up and leave any time. Pay that experienced designer say 80k PA ($40/hr) , say they do that type of work 65% of the time that they work for you equals a real productive cost of $185/hr.

The benefit of employing us is that our fee rates range from $90 to $175 per hour, we have around 250,000 man hours of data based information on tap, we have a range of skilled individuals to call on, we are totally confidential, have been around for 22 years and intend to be around for much longer

Bearing in mind the above, Randall and Associates Ltd would like to offer a helping hand, by way of fixed fee service contract, to all good operators, manufacturers and suppliers on a national basis which recognizes your excellent standing in the community. We would undertake the following services on a national basis

• “Design and certification” and or “design and issue of statements of design compliance” covering all aspects of heavy vehicle manufacture or modification
• Sales drawings, promotional drawings, concept sketches
• Provision of standard designs specification either on our letter heads or yours

The benefits to you of a fixed fee contract are

• You just pick the phone up and ask for something to be done—you do not have to worry about cost,
• Better staff utilization,
• National coverage, national consistency for design and specification,
• Reduced compliance and design hassle (one organization to work with).

The benefits to us:

• Better use of our staff and expertise,
• Better use of our data based knowledge,
• Better way for us of dividing up the work day.

Call to action—contact Nigel to find out more

The following is an article I wrote for an IPENZ website. I thought it might be a great way to start my blogging career, and will let you learn a bit about me and my company…….

Randall and Associates, a mechanical engineering consultancy, employed me after I had completed a BE(Hons) in Mechatronics from Massey University. In the final months of my degree I was job searching and it wasn’t a matter of finding a job, but choosing the one I liked the sound of the most. With Randall and Associates specialising in the heavy vehicle industry and earth moving machinery, I was drawn to this type of consultancy.

When I began, I joined a team designing a fatigue towbar tester. This projects purpose was to mechanically test towbar designs (simulate the life of towbar in hours not years) before they were mass produced. Signal processing, linear displacement, force measurement, hydraulic monitoring and controlling as well as data acquisition and processing were all involved throughout design, manufacture and support for this project.

Other projects include heavy vehicle chassis design, towing connections, truck and trailer bodies, excavator, roller, bulldozer, grader roll over protection structures, cab risers, falling object protection, operator protection, and body protection for the use of general contractors and for the use forestry applications. Theses projects require design by 2D and 3D modelling, finite element analysis and hand calculations. The forwarding of information to clients requires manufacturing drawings to current and relevant standards.

Working for a consultancy allows me to utilise the knowledge obtained at university and the knowledge I am forever learning in the workplace, combined with the latest software packages and the knowledge of my colleagues to provide my clients with the best solution to their engineering problem.

Working in a consultancy allows diversity throughout my career. With Randall and Associates having fewer than 10 employees we have become adaptable to clients needs. This allows us to become multi skilled in our industry and with customers coming up with more and more challenging circumstances, the expectation for designs to meet their needs grows. The variety of tasks enables me to be forever learning, this is shown by the commitment of the management at Randall and Associates by sending myself and other staff on career furthering block courses to stay one step ahead of the opposition

When Randall and Associates is approached to solve an engineering problem and I become involved in the solution, a degree of satisfaction and accomplishment is achieved when the project is completed. Direct contact with the clients throughout the projects allows no miscommunication and my job becomes more than just engineering but project and time management. For all this my job never becomes stagnant and the rewards for constant customer approval and satisfaction keep the job enjoyable.

We invite and encourage comments. If you would like to comment on this post – or suggest a new item for discussion, please click on the (No) Comments link below. It’d be great to hear what you are thinking!