From: Isabel Hadley
Send: vr 11-07-03 17:24
Weldolet computer calculation

Dear Paul,

Beautiful website! In my web searches, I found the document 'computer calculation of a weldolet' on your site, but was unable to access it because I need a password.
Basically, we have just been carrying out FEA of a weldolet on a high-pressure piping system and were surprised to find very little information on the design and analysis of weldolets in the open literature. I would be very grateful if you could send me your information - if I use it, I will, of course, acknowledge the source.

Dr Isabel Hadley

Defect Assessment Section,
Structural Integrity Technology Group,
TWI Ltd, Granta Park, Great Abington,
Cambridge CB1 6AL, UK
Tel +44-1223 891162 x2473
Fax +44-1223 893303
TWI has a web page on

From: Dave Diehl
Send: di 17-06-03 18:52
Re: Mail from Pipestress Website:


I have had a few requests for NEN-3650 and came across your web site trying to learn more. I have asked someone to buy me an English version of the NEN code and will correlate that document with your piece once I receive it.

The interest came from someone who doesn’t like our buried pipe modeler. He suggested the NEN document.

I agree with you about user knowledge and/or experience. But I see it a different way. As we add new analysis capabilities to the program, more information is required of the user to properly utilize the capability.
For example, we ask some simple soil parameters to define our restraints. It is not uncommon for a user, who knows we have this capability, to introduce himself to this field simply by reviewing our input requirements and have no idea what these parameters are or how they are applied.

Pipe stress analysis used to be a specialist application. With today’s software, management (incorrectly) assumes the generalist can do it.

Thanks for the articles.

I’ll keep in touch.


From: Choudhary Ranjeet SPEL-T2
Send: wo 25-06-03 12:09
Mail from Pipestress website

Dear Mr. Voorhaar,

I was on the Web Site Pipestress and should thank you for the splendid work done by you here, which is surely of lot of help to all the piping engineer community.
I am interested on the paper computer calculation of weldolet. Can you please provide me with the password to open this page.

Thanks again,

From: shankar shrivastava
Send: ma 12-05-03 2:52
Re: Mail from Pipestress Website:------

Dear Paul,
Thanks for your response.
I could access the article.

Your article shure looks a great food for thought. The information from various sources (references) you have consolidated indeed reveals the indepth look you have had into this matter.
Over the next couple of weeks I shall try to imply them for practical purposes.
I shall be very thankful if you could provide me access to the two related articles

'Case study of Delta Stretching of current flow velocity' &
'Wave Loadings on an offshore riser'

Best Regards,
Shankar Shrivastava
PT SemPec

From: shankar shrivastava
Send: ma 05-05-03 9:02
Mail from Pipestress Website:------

Hi Paul,
Could you please provide me an access to the article
'Case Study of wave loadings on an offshore pipeline'

Thanking you,
Shankar Shrivastava
Piping - Betara Complex Development
Sembwang E&C

From: Sergio Urtiaga
Send: za 03-05-03 4:25
birds and other coincidences

Mr. Voorhaar,
I am sincerely pleased to meet you in the web. Your page is very good.
The photos are really great!! I am the visitor number 22722 or so. I am very fond of bird watching, but ocational, and amateur. I have no special equipment (400 or bigger tele) neither never make special trips to see the birds, but here in Argentina, you can find them every where. I send you three pictures. The humbird (we call him "picaflor" o "colibri"), comes every day to our window at five o´clock. The foto was taken with a 200mm tele. The other one, is a kind of woodpecker ("pajaro carpintero") was taken in a National Forest near San Carlos de Bariloche, with a 150mm tele. I spent almost a film roll, because is allways beating his head against the tree, and moves it so fast, that you cant fix the image. 1/1000sec to freeze, and you have no light, because the forest is dark. If you are patience, you can find them very near. The third picture is the "Hornero", he and she construct his nest with mud and straw, and is a prefect sphere. The picture is really bad, but you can see him in the construction process.
The second coincidence it is that am FEA analist, very interested in pipe stress, but also pressure vessels and civil structures. As you know Argentina is a very little country, in economics terms, though geographicaly speaking is very large, and as professionals we need to broad our target, and in consequence loosing deep of knowledge. I should like to read your paper about design of weldolets. The third coincidence is that I was born in 1949 to. My english is really poor, I hope you had understood my words
Best regards
Sergio Urtiaga

From: M.Nuttpon
Send: do 06-03-03 13:23
Require the password

Dear Mr. voorhaar,

It's a cool and interesting web site about  pipe stress.
My main responsibility is the pipe stress analysis in pressure pipeline in several power plants ,I 'm sure that there are many articles in your website that will  be good for me and my colleagues for sure.
So I would like you to provide me  the password for approching some articles  in order to study respective case studies. I have no idea the password can be used together for
Case study of wave loadings on an offshore pipeline " and " Case study of Delta stretching of current flow velocity "
If they are different, please give me both.

Your kindness will  highly be appreciated and thank you in advance.

Best regards

From: Clark, Kevin
Send: vr 21-03-03 16:37
Mail via Web page 

Mr. Voorhaar,

I am a design engineer in Denver and I am very interested in viewing/downloading some of the excellent articles on your site. How do I get a password?
Specifically I am very interested in the different stress allowed by the different codes and how the Factors of Safety (FOS) are integrated.
Please contact me at your convenience via email.

Thank you for your consideration,
Kevin Clark

From: Othón Brindis
Send: wo 12-06-02 0:41
Mail via Web page

Dear Mr. Voorhaar,

I have just discovered your very interesting specialized web site and I believe it deserves a lot of attention.

My background is Civil Engineering, and I was involved as a lead pipe stress engineer in several projects, all related with Petrochemical and Offshore industry.
I found your web site while searching the internet for Pipe Stress issues.
I've found your site quite interesting.
I would like to review some of your articles in the "Hot Issues and
Technical Discussions" section but a password is required. May I get a password for this please?
I'm a Piping Engineer in Mexico, City with 17 years experience.

Thanks in advance,

José Othón Brindis Sandoval.

From: Angel Amores Info
Send: dinsdag 7 mei 2002 5:18
Subject: Mail from Pipestress Website

Hace varios dias, les envié una consulta y quisiera ampliarla, quisiera saber que software debo instalar en una fabrica de maquinaria para fabricar cartón, necesitamos soluciones del tipo CAD-CAE, para diseñar las maquinas y los elementos que las componen, haciendo simulaciones de ensayo de los elementos moviles y calculos de esfuerzo para diferentes materiales, ademas necesitamos organizar los planos de los diferentes modelos de máquinas, asi como sus componentes.
Les ruego me envien información de los programas, precio y si es necesario hacer un curso de aprendizaje.
Muchas gracias. Angel Amores.

From: Marian Nicolescu
Send: di 09-04-02 14:36

Dear Mr. Voorhaar,

I have just discovered your very interesting specialised web site and I believe it deserves a lot of attention.
My background is Mechanical Engineering, and I was involved as a lead pipe
stress engineer in several projects (Romania and Middle East), all related with Petrochemical industry.

The software currently I use is CAESAR II.
Since I would like to study some of the technical papers listed on your
site, could you send me the passwords for: SP102006.pdf and VVRDEGID.pdf ?

Best regards,

Marian Roman Nicolescu

From: Monroe, Kevin
Send: wo 20-03-02 21:04


I found your web site while searching the internet for Pipe Stress issues.
I've found your site quite interesting.

I would like to review some of your articles in the "Hot Issues and Technical Discussions" section but a password is required. May I get a password for this please?

I'm a Piping Engineer in Houston, Texas with 25 years experience.

Thanks in advance,
Kevin Monroe

From: Leonard Stephen Thill
Send: do 14-03-02 10:20

Dear Mr. Paul Voorhaar,

Thanks you for your e-mail of today.
Just think about this: You may remember GOS PROJECT, Yes!
Gas Oil Septatin Plant, Aramco, Abqaiq, Saudi Arabia 1977-1987

Nice to hear from you after all those years.

Stephen Thill

From: systech consultancy services
Send: Wednesday 21 November 2001 17:58
Subject: Response on website via form on pipestress startpage

Good site! I fully agree with your comment that, " Although most quality systems are duly certified according to ISO 9001, this does not guarantee that the stress reports are complete or correct". It reminds me that, "purpose of computing (in our case stress analysis) is not in numbers (our case stress or deflection) but insight ("how piing will behave for new plant " or " how it behaved for as-built plant where it failed").

Here is some details about my association with field of stress analysis.
Has been providing piping design with stress analysis since 1972 when I
came back after graduate studies in Mechanical Engineeing from Carnegie Mellon University. Used IBM 1620 program, converted to IBM/360, then DEC-10, DEC-20, Vax. Then modified SAP4 to do Piping code calulation ( ASME/ANSI B 31.3) till 1985 when visit on the way to SwRI to attend short course on Compressor, stopped at to AAAT (Now),Houston resuled in our being their Indian rep and has been using TRIFLEX. Offcourse I use FEA tools for more complicated analysis / failure analysis and own simulation program for pulsation studies.

We have rectified large number of plant piping designed by leading European, American and Japanis firms and have solved recip.compressor problems for Indian arm of Dutch firm (Shell), analog reports of SwRI and TPD.

D. H. RAWAL, B.E.,M.E.,M.S.(U.S.A.)
055, INDIA.
PHONE: 91-22-618-4506 or 618-4787, FAX: 91-22-618-2737
E-MAIL: or

Visit us at:

TO: Mr Paul Voorhaar
AT: Voorhaar en Partners
Copies: Inger de Ru
Date: 20 XI 2000

Geachte heer Voorhaar
SUBJECT: Pipe Stress Analysis Programmes

Uw adres vond ik op het Internet als specialist op dit gebied, maar helaas niet uw telefoonnummer. Binnenkort ontvang ik een handelsmissie vanuit de UK die contacten zoeken in Nederland waarvan een op het gebied van plant design en automation. Zou graag even hierover met u praten als dat lukt.

Met vriendelijke groeten,


Leo Zonneveld
Commercial Officer
High Technology Products
British Embassy
Lange Voorhout 10 - 2514 ED The Hague
Tel: 00 31 70 4270 304
Fax: 00 31 70 4270 346
See UK Exporters Database at:
Whereas every effort has been made to ensure that the information given herein is accurate, British Trade International or its sponsoring partners, The Departments of Trade and Industry and the Foreign and Commonwealth Office, accept no responsibility for any errors, ommissions or misleading statements in that information and no warranty is given or responsibility accepted as to the standing of any firm, company or individual mentioned.

From: John Luf
Send: Wednesday August 23 2000 15:05
Subject: Greetings from America

Servus Paul,

I love your site and your statements.... But then I'm another grumpy old guy with a lot of experience as well. Better to be smooth and slick for the bosses today. Anyhow back to work, I will check in again from time to time...

(Why Servus??? Mein Mutter und Vater were Osterreichers, I was the first born in the USA, seeing as how you are a "hollander" I thought I would use a Euro touch)

With Best Regards From Cleveland, Ohio USA

John C. Luf

From: Harry de Groot
Send: Tuesday, March 21, 2000 at 11:33
To: 'Voorhaar, Paul'
Subject: HEC E_mail adres en HomePage

(Partly translated from Dutch) 

Dear Paul,

It has been a longtime since I have spoken with you.
I found your site on the Internet by coincidence. I heard about it through the grapevine. It looks good, I only wonder how it can become a knowledge exchange platform. I don’t see anything from 2000.
The reason for this mail is a little addition. We do have our homepage for some time now and are very busy with creating and promoting it. You can know make a link to it in the table with Pipestress software. The data are at the bottom of this mail. 


Oh well Paul, I wish you all the best. Let’s hear from you. 

Harry de Groot
Consulting Engineer

Holland Engineering Consultants bv,
Mailbox: 1359 NL_3430 BJ NIEUWEGEIN
Tel: +31 (0)30 600 60 60
Fax: +31 (0)30 600 60 61
Hotline: +31 (0)30 600 60 66

on Friday, July 2, 1999 at 23:27:51

Dear Paul W. H. Voorhaar,

Some very interesting information, looking forward to seeing some of the articles translated to english (although both my parents were born in the Netherlands, I cann't read or speak Dutch).

Interesting concept of providing a list of professional engineers with a speciality in pipe stressing.
Looks like I have to wait another five years before being eligable for the list, have been an engineering since 1975, but only involved pressure equipment design including piping since 1990.

Keep up the good work.

Kind regards.
Frank Hendriks

City: Woodend
address: PO Box 360
Postal_code: 3442

State: Victoria
Country: Australia

) on Tuesday, August 3, 1999 at 20:00:03

Subject: Request for linking this site to an other interesting site.

I have noticed that your website has articles, etc. about various engineering subjects. I would like you to check out our "tip of the month" and possably add a link to it.

George A. Starkey
City: San Jose
address: 1641 North First St. Ste. 175
Postal_code: 95112
State: CA
Country: USA
Phone: (408)452-8111
fax: (408)452-8388

Checked out and incorporated

on Friday, July 2, 1999 at 11:25:34
Subject: NEN3650 software

Dear Sir,
You must know CEA systems as the distributor of CAESAR II and CAE Pipe.
Your web-site is most impressive, most of our current users could be found on your website and the technical foundation is very strong.

I have a question: you mention the vendor R&K Consulting engineers for the program PLE. Could you give me a lead to contact them as I want to look for good software acc. to NEN 3650.

James Tauladan,

CEA Calculation

R+K Consulting engineers

Geestbrugweg 44
2281 CM Rijswijk ZH
The Netherlands
Phone: 31 70 390 68 90

on Saturday, December 26, 1998 at 09:30:04

name: Mr. Misa Jocic

Dear Mr. Voorhaar,

It was very pleasing to discover your web-site dedicated to piping stress analysis engineers. The only unclear aspect to me was whether it is addressed only to Dutch engineers or to a wider international community of piping stress analysts.

Presently I am working as a Principal Stress Analysis Engineer with Shedden Uhde in Melbourne, Australia. Likewise, I had to certify numerous calculations of fellow pipe stress analysts and in 17 years of my experience many times witnessed cases of misuse of computer software in engineering design. Quite often I had discussions with colleagues about this worrying trend and was delighted when I saw that someone on the other side of the globe has actually started a campaign on this topic.

In Australia, there is no organisation such as Stoomwezen, so we are even more exposed to the syndrome of "smooth talking colleagues", "least trouble equals good performance" and "managers who make profit their only objective". It has all indeed contributed to the decline in quality and safety of designs.

Not long ago however we did have a body called D.O.L. (Department of Labour) which had a mandate at least on paper, to perform verification of piping stress analysis. Unfortunately this function has been taken away from them and piping stress analysis has become a sole responsibility of clients and consequently engineering design and consulting firms. Many companies such as ours in order to protect themselves have developed comprehensive piping stress analysis procedures and guidelines. The verification is occasionally subcontracted to outside companies but most of the time, for obvious cost reasons performed within the company by an engineer not directly involved on the project.

In spite of the fact that all this satisfies and probably exceeds the requirements of Australian code and ISO 9001, it still is not enough to guarantee that stress reports are complete or correct. In my opinion, no administrative measure will be able to guarantee this because as you pointed out, no person is the same and there are various approaches in solving similar problems. For the same reason, much is always going to be dependent on the experience, knowledge and other qualities of an individual stress analyst.

I believe that it is an excellent idea to form a database of graded experienced stress engineers and would be more than happy to provide you with my CV should you be interested.

This even more so because I have been forced for family reasons to seek an alternative position in Western Europe at the beginning of next year.

My expertise is in piping stress analysis and would be best suited for companies that employ CAESAR II, CADWorx, PDMS and FE/Pipe. The highlight of my latest achievements is the development of PDMS to CAESAR II transfer tool via CADWorx.

The article on this topic titled "Genesis of PDMS to CAESARII Transfer Tool" has been published in COADE Mechanical Engineering News, Volume 25, June 1998.

I believe you will find my background and experience engaging and look forward to hearing from you soon.

Yours sincerely,

Misa Jocic