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Comparing Iso13709 / Api 610 With Ansi / Asme B73.1 Centrifugal Pumps




Comparing Iso13709 / Api 610 With Ansi / Asme B73.1 Centrifugal Pumps I am not a rotating machinery specialist but a process engineer. Today's blog heading probably has more relevance to a rotating machinery specialist. Nevertheless, I felt that process engineers are also entitled to know the difference between these two distinct categories of centrifugal pumps used worldwide for a majority of pumping applications involving centrifugal pumps.

One of the foremost rotating machinery and reliablity specialist of our times is Heinz P. Bloch with numerous books, articles and research papers on rotating machinery and machine reliability. His fame as a machinery specialist is such that Wikipedia has an article on him. Refer the link below:

http://en.wikipedia..../Heinz_P._Bloch

The comparison that I am providing is referenced from his book "Pump User's Handbook Life Extension" co-authored with Allan R. Budris

ANSI vs API

Compared to an API pump, the typical ANSI pump has the following characteristics:

1. A thinner casing, i.e. less corrosion allowance

2. An ANSI pump has reduced permissible nozzle loads. It is even more sensitive to pipe-induced stresses than the API pump.

3. An ANSI pump has a smaller stuffing box size. Unless a large bore option is chosen, an ANSI pump may not be able to accomodate the optimum mechanical seal for a given service.

4. ANSI pump impellers are designed and manufactured without wear rings. Many ANSI pump impellers are open or semi-open whereas API pumps feature closed impellers with replaceable wear rings.

5. ANSI pumps are generally foot-mounted, whereas the API pump will be centerline mounted. Refer the attached sketch. In foot-mounted pumps casing heat tends to be conducted into the mounting surfaces and thermal growth will be noticeable. It is generlly easier to maintain alignment of API pumps since their supports are surrounded by the typically moderate-temperature ambient environment.

Attached Image

The decision on API vs ANSI construction is experience-based and is not governed by governmental or regulatory agencies. However, experienced machinery specialists have their own likes and dislikes based on the experience gathered by them over their long years in the machinery field.

Many highly experienced and reliability-focused machinery engineers would prefer to use pumps designed and constructed according to API 610 for toxic, flammable, or explosion-proof services at on-site locations in close proximity to furnaces and boilers in some of the conditions (rules-of-thumb) that are listed below:

a. Head exceeds 106.6 m (350 ft)
b. Temperature of pumpage exceeds 149°C (300°F) on pumps with discharge flange sizes larger than 4 inch or 177°C (350°F) on pumps with 4 inch discharge flange size or less.
c. Driver horsepower exceeds 74 kW (100 hp)
d. Suction pressure in excess of 516 kPag (75 psig)
e. Rated flow exceeds flow at best efficiency point (BEP)
f. Pump speed in excess of 3600 rpm.

The author mentions that there have been exceptions made where deviations from the rules-of-thumb were minor, or in situations where the pump manufacturer was able to demonstrate considerable experience with ANSI pumps under the same, or even more adverse conditions.

Finally the author gives his opinion on choosing either API or ANSI pumps based on the following:

Conventional Wisdom: API-compliant pumps are always a better choice than ANSI or ISO pumps

Fact: Unless flammable, toxic or explosion-prone liquids are involved, many carefully selected, properly installed, operated and maintained ANSI or ISO pumps may represent an uncompromising and satisfactory choice.

Hope readers of my blog like this comparison of API & ANSI pumps provided by one of the foremost machinery specialists of our time.

Let me have your comments on this blog entry.

Regards,
Ankur.




You forgot to mention price (API is more expensive) and design. A good reputable ANSI pump can get close to an API pump in "durability", but they tend to be the exception due to competing with lower quality manufacturing lines that skirt around the standards. In general, it it's critical (e.g. nuclear) or you need very long durability (e.g. oil platform), API is the way to go. If the pump is easily serviced in non dangerous environments (e.g. water treatment), ANSI/ISO is the cost effective way to go (especially from good brands)
One further difference between ANSI and API pumps is the vast allowed variation between manufacturing tolerances that will later cause you operating failures.

For example, baseplate surface un-flatness on ANSI pumps is permitted to be as bad as 0.375 mm per metre (0.005 in/ft)... this tolerance will cause you soft-foot problems. Whereas for an API pump the maximum allowed un-flatness is 0.150 mm/m (0.002 in/ft)... this standard will cause few soft problems unless at the extreme allowance range.

It made me laugh when I first realised that as an engineer you can buy a new ANSI pump and unknowingly bring endless breakdowns into your company because the manufacturer built-in a soft-foot problem for which you happily paid them.

By the way, an un-flatness tolerance of 0.002 in/ft is not even a challenge with today's fabrication methods and machining tools. You should be asking for 0.0005 in/ft as maximum un-flatness; that will stop soft-foot breakdowns being designed into your machines.
Thak you for this valuable post,

Please I want to know diffrence between API and ISO pumps in term of performance and performance testing.

For experienced rotating machinery specialists, please advice about diffrence between NFPA20 pumps and ISO 5199 pumps in term of performance limits and performance testing. Could a pump be at the same time in coformity with NFPA20 but tested with ISO 2548.

Many thaks in advance.
For anyone interested, I have a copy of a technical summary comparing API610, ANSI B73.1M and ISO 5199 pumps. Also, API 610 8th Edition gave guidelines for the selection of non API 610 compliant pumps (Section 1 - General, paragraph 1.1.4). No doubt the selection of API 610 pumps for all duties in refinery service would likely give an extremely robust pump, but in circumstances where a more lightly constructed pump, in relatively non-hazardous service would suffice, there are massive savings in cost and much reduced lead times for appropriate ANSI/ISO standard pumps
Hi Jet1749,

I am interested in receiving a copy of your summary. Will you please send to me at roger.blanton@johnzink.com?
thank you in advance for your kind consideration.
I also intereseting to recieve a copy of your summary, please send me to this email address p.jimenezs@yahoo.es

thanks in advance
I also intereseting to recieve a copy of your summary, please send me to this email musawyq@yahoo.com.cn
thanks in advance
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engr_cortes
Jan 28 2013 08:16 PM
Hi jet good day..I work as an associate design engineer 1 in a petrochem industry..could you send me a file for ANSI and API differences. my email account is Jay.Allan.Cortes@fluor.com. thank you very much jet
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ramsingh_mech
Mar 18 2013 11:52 PM

Hi Jet ,

 

Could u pls send me a copy. ramsingh_mech@yahoo.com

Ram.

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ramsingh_mech
Mar 18 2013 11:54 PM

Dear Ankur Sir ,

 

Could you pls suggest me a good hand book for Rotary Equipment Engineering.

It would be very helpful , if u send me any good attachments.

 

Thanks

Ram.

Dear Ankur Sir ,

 

Could you pls suggest me a good hand book for Rotary Equipment Engineering.

It would be very helpful , if u send me any good attachments.

 

Thanks

Ram.

Ram,

 

Refer the books mentioned under compressors and pumps in the link below:

 

http://www.cheresour...gn-engineering/

 

Regards,

Ankur.

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RABAIOLI_MATTEO_75
Apr 11 2013 06:57 AM

Hello Mr Ankur,

I would be very pleased if you could send me a copy of your summary.

 

 

Here is my address: m.rabaioli@eurotecnica.it

 

 

Thanks in advance 

 

Regards

Matteo Rabaioli

Hello jet1749, would you please send me a copy of the technical summary comparing the different standards. My e-mail address is anish.chaudhary@ril.com.

 

Thank you very much.

 

Regards

 

Anish

Hello

 

could you send me a copy of technical summary comparing different std? angelodomrizzo@hotmail.it

 

 

Thank a lot

hi..

anyone who received the technical summary please send to rk.bits2004@gmail.com

Hello jet1749, would you please send me a copy of the technical summary comparing the different standards. My e-mail address is binaywatch@yahoo.co.in

hye mr/mss jet1749, appreciate if you can share the said document to my email: irfaridkarim@gmail.com
 
tq very much

Can anybody send me a copy of this technical summary to my e-mail balascio@invap.com.ar

Thanks 

like the forum and have been in pump industry for 27 years and have a lot of technical info but most is branded or company specific. I wrote a comparison between these standard up to 8th edition but mostly ran out of time to ammend to latest. Mostly API610 8th to 11th was changes to documentation and introduction of API682 for seals. Glad to help as in individual cheers and excellent posts

Hi Jet1749,

I am interested in receiving a copy of your summary. Would you please send it to me at

tariqsadek@yahoo.com

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