Roundup of Things API 610 got Wrong

Hi everyone. This is just a brief roundup post to make readers aware of the subjects covered in parts 1 to 7 of my series: Things API 610 got Wrong.

To be honest this is as much for myself as it is for you - as I tend to forget what each part of the series covered. So having a handy summary, will help ease my aging recollection.

So without further embellishment or killer Wombats, here they are. There are hyperlinks to each article so if you find one that interests, please don't be shy about clicking on it:

What API 610 got Wrong #1

6.1.8 - Disallowing a correction factor for NPSH3

This clause of API 610 was established in 1995 with the 8th Edition version. It states:

6.1.8 The vendor shall specify on the data sheets the NPSH3 based on water [at a temperature of less than 55°C (130°F)] at the rated flow and rated speed. A reduction or correction factor for liquids other than water (such as hydrocarbons) shall not be applied.

What API 610 got Wrong #2

6.1.12 - Relying solely on percent of best efficiency flowrate as the indicator of a reliable pump selection

This clause of API 610 states:

6.1.12 Pumps shall have a preferred operating region of 70 % to 120 % of best efficiency flowrate of the pump as furnished. Rated flow shall be within the region of 80 % to 110 % of the best efficiency flowrate of the pump as furnished.

What API 610 got Wrong #3

6.1.11 - Relying solely on a minimum 10% head rise to shutoff to prevent reliability problems when operating pumps in parallel

This clause of API 610 states:

6.1.11 Pumps that have stable head/flowrate curves (continuous head rise to shutoff) are preferred for all applications and are required if parallel operation is specified. If parallel operation is specified, the head rise from the rated point to shutoff shall be at least 10%...

What API 610 got Wrong #4

6.3.4 - Disconnecting API 610 from accepted pressure vessel design codes while at the same time forcing continued reliance on those same codes.

This clause of API 610 states:

6.3.4 The tensile stress used in the design of the pressure casing for any material shall not exceed 0,25 times the minimum ultimate tensile strength or 0,67 times the minimum yield strength for that material, whichever is lower, across the full range of specified operating temperatures...

What API 610 got Wrong #5

6.3.9 - Continuing to rely on widely ignored pressure and fluid density limits for axially split pumps and not updating the limits to better reflect the current science and expanding application usage for these pumps.

This clause of API 610 states:

6.3.9 Unless otherwise specified, pumps with radially split casings are required in services for any of the following conditions:

a) pumping temperature of 200 C (400 F) or higher (a lower temperature limit should be considered if thermal shock is probable);

b) liquids with a relative density of less then 0,7 at the specified pumping temperature;

c) liquids at a rated discharge gauge pressure above 10 MPa (100 bar; 1450 psi).

What API 610 got Wrong #6

7.4.2 - Outsourcing recommendations on appropriate pump instrumentation to API 670 while failing to ensure API 670 adequately covers the monitoring needs that are specific to pumps.

This clause of API 610 states:

7.4.2.1 If specified, accelerometers shall be supplied, installed and tested in accordance with ANSI/API 670

7.4.2.2 If specified for equipment with hydrodynamic bearings, provision shall be made for mounting two radial-vibration probes in each bearing housing, two axial- position probes at the thrust end of each machine, and a one-event-per-revolution probe in each machine. The purchaser shall specify whether detectors shall be supplied. The detectors and their mounting and calibration shall be supplied, installed and tested in accordance with ANSI/API Std 670.

7.4.2.3 If specified, hydrodynamic thrust and radial bearings shall be fitted with bearing metal detectors. If pressure-lubricated hydrodynamic thrust and radial bearings are supplied with temperature detectors, the detectors and their mounting and calibration shall be supplied, installed and tested in accordance with ANSI/API Std 670.

7.4.2.4 If specified, monitors with cables connecting to vibration, axial-position or temperature detectors shall be supplied, installed and tested in accordance with ANSI/API Std 670.

What API 610 got Wrong #7

6.10.2.7 - Setting a maximum pump bearing oil temperature rise, but then failing to provide simple robust guidance or consider what happens when the exact same pump bearing is operated or tested in low ambient temperature.

This clause of API 610 states:

6.10.2.7 Sufficient cooling, including allowance for fouling, shall be provided to maintain oil and bearing temperatures as follows during shop testing and in field operation under the most adverse specified operating condition:

b) for ring-oiled or splash systems (including such systems with purge-oil mist), the sump oil temperature rise shall not exceed 70 °F (39 K) above the ambient temperature, and if bearing-temperature sensors are supplied, bearing metal temperatures shall not exceed 200 °F (93 °C);

As always I am very grateful to any of my readers who take the time to give feedback, comments, suggestions or criticisms. If there are any questions those too are gratefully received.

Obsesio positivum

#pump #API610 #centrifugalpump