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- since 1996 -
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Marius Dinu
NDT Inspector, Pre-service and In-Service Inspections
General Electric - Life Extension Services, Romania, Joined Oct 1999, 5

Marius Dinu

NDT Inspector, Pre-service and In-Service Inspections
General Electric - Life Extension Services,
Romania,
Joined Oct 1999
5
09:48 Feb-11-2004
Re: corrosion rate
----------- Start Original Message -----------
: I would like to know if there is any interesting site or article regarding the latest technique/method and calculation on determining the corrosion rate using UT thickness gauging.
: Apart from calculating using Barlow's formula and maximum-energy-of-distortion theory to determine the minimum thickness of pipe, is there any method or standards to determine the minimum allowable thickness of pipe ?
: Appreciate the help.....
: Thank you and warm regards
:
------------ End Original Message ------------

Try ULTRAPIPE. This is a specialized software for thickness monitoring and it includes also a minimum thickness calculator (as per various standards and codes). Based on the UT surveys, this software gives you the corrosion rates and can calculates also the remaining life of the pipe (equipment). You can find a demo at www.ultrapipe.com

Regards,

Marius Dinu



    
 
 Reply 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 278

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
278
05:18 Feb-12-2004
Re: corrosion rate
API RP 579 covers Fitness For Service particularly for process equipment and goes beyond the Barlow Formula.

There is a 579 FFS Training Course in Shah Alam malaysia in June contact itc@intestmal.com





    
 
 Reply 
 
luis marques
luis marques
08:32 Aug-04-2004
Re: corrosion rate
If it will be helpful for you accept the transcription bellow, only as a guideline. Regards

Luis Marques

Determination of MAWT

Minimum Acceptable Wall Thickness (MAWT) shall be calculated in accordance with the ASME VIII equations. Corrosion allowance should not be considered when using these equations.

Example: For a cylindrical shell (longitudinal joint):

MAWT = PR/SE-0.6P (1)

P = Design pressure (psig) R = Inside radius of vessel (inches) S = Stress value (psi) from table UCS-23 (ASME VIII) E = Joint efficiency factor from table UW-12 (ASME VIII) Determination of Corrosion Rate

From API 510, the following equations shall be used to determine long term (CRLT) and short-term (CRst) corrosion rates. Corrosion rates are expressed in mils (thousandths of an inch) per year (MPY).

CRLt = 1000(tI-tL)/ time (years) between initial and latest inspection) (2)

CRLt = 1000(tP-tL)/ time (years) between previous and latest inspection) (3)

Where: TL = Thickness of wall at most recent survey(inches) TP = Thickness of wall recorded in previous survey (inches) TI = Thickness of wall recorded in baseline survey (inches)

Determination of MAWPCURRENT

The current Maximum Allowable Working Pressure (MAWP) shall be calculated using the following ASME VIII equations.

Exemple: For a cylindrical shell (long seam):

MAWPCURRENT =SEt/ R+0.6t (4)

S = Stress value (psi) from table UCS-23 (ASME VIII) E = Joint efficiency factor from table UW-12 (ASME VIII) R = Inside radius of vessel (inches)

Forecast Inspection Interval

It is possible to make a decision as to whether inspection frequency may be increased or decreased, or whether the vessel should be repaired, by considering the worst case corrosion rate and estimating the wall thickness at the date of next inspection. The worst-case corrosion rate may be either CRLT or CRST.

Estimated wall thickness loss at date of next inspection may be calculated in accordance with API 510 using equation (5) below.

tEST = (CRwc/1000) X (Years to next inspection) (5)

Where:

tEST = estimated thickness loss at the date of next inspection (inches)

CRWC = worst case corrosion rate (MPY)

Determination of Remaining Life

Remaining life in years shall be calculated for each vessel using the equation below,

REMAINING LIFE (YEARS) = 1000(TL – MAWT)/CRwc (6)

If remaining life < time to next inspection then one of the following actions must be taken:

1) Inspection frequency must be increased to closely monitor deterioration prior to failure 2) The vessel must be repaired or retired.

Luis Marques





    
 
 Reply 
 
Er.R.Elansezhian, M.E.,
Er.R.Elansezhian, M.E.,
08:31 Oct-13-2004
Re: corrosion rate

I would like to know the formula for determing the corrosion rate of a metal by weight losss method.
available datas are:
Initial weight, final weight, time of exposure, area of specimen,
thanks & regards
sezhian----------- Start Original Message -----------





    
 
 Reply 
 
Ed T.
Ed T.
09:38 Oct-13-2004
Re: corrosion rate
----------- Start Original Message -----------
:
: I would like to know the formula for determing the corrosion rate of a metal by weight losss method.
: available datas are:
: Initial weight, final weight, time of exposure, area of specimen,
: thanks & regards
: sezhian----------- Start Original Message -----------
------------ End Original Message ------------
You may want to try this links or the ASTM Standard listed below:

http://www.astm.org/DATABASE.CART/workitems.htm

D2688-94(1999)e1 Standard Test Methods for Corrosivity of Water in the Absence of Heat Transfer (Weight Loss Methods)


    
 
 Reply 
 
A. Emami
A. Emami
04:19 Nov-19-2004
Corrosion Calculation
----------- Start Original Message -----------
: : I would like to know if there is any interesting site or article regarding the latest technique/method and calculation on determining the corrosion rate using UT thickness gauging.
: : Apart from calculating using Barlow's formula and maximum-energy-of-distortion theory to determine the minimum thickness of pipe, is there any method or standards to determine the minimum allowable thickness of pipe ?
: : Appreciate the help.....
: : Thank you and warm regards
: : Ayat
: Try ULTRAPIPE. This is a specialized software for thickness monitoring and it includes also a minimum thickness calculator (as per various standards and codes). Based on the UT surveys, this software gives you the corrosion rates and can calculates also the remaining life of the pipe (equipment). You can find a demo at www.ultrapipe.com
: Regards,
: Marius Dinu
------------ End Original Message ------------




    
 
 Reply 
 
Atef
Atef
00:35 Feb-03-2005
corrosion rate

Hi Sir
I would like to know the formula for determing the corrosion rate of a metal by weight losss method.


Best Regards,
Atef
Suez Canal University, Egypt


    
 
 Reply 
 
Ed T.
Ed T.
09:17 Feb-07-2005
Re: corrosion rate
----------- Start Original Message -----------
:
: Hi Sir
: I would like to know the formula for determing the corrosion rate of a metal by weight losss method.
:
: Best Regards,
: Atef
: Suez Canal University, Egypt
------------ End Original Message ------------

Try these links:

http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1110.pdf

http://www.corrosion-doctors.org/MonitorBasics/coupons.htm




    
 
 Reply 
 
frances
frances
05:32 May-20-2005
corrosion
hi i was just wondering if you could help me calculate the rate of corrosion, for different metals from the following information.Eg 1. iron: density=7.87, oxidation state=2, corrosion current density = 2.5 time 10 to the power -4, and atomic weight = 55.8 grams per metre thank you very much ive just hit blank.

Frances


    
 
 Reply 
 
chinedu anderson
chinedu anderson
02:53 Aug-19-2005
corrosion rate
----------- Start Original Message -----------
: :
: : I would like to know the formula for determing the corrosion rate of a metal by weight losss method.
: : available datas are:
: : Initial weight, final weight, time of exposure, area of specimen,
: : thanks & regards
: : chinedu anderson

: You may want to try this links or the ASTM Standard listed below:
: http://www.astm.org/DATABASE.CART/workitems.htm
: D2688-94(1999)e1 Standard Test Methods for Corrosivity of Water in the Absence of Heat Transfer (Weight Loss Methods)
------------ End Original Message ------------




    
 
 Reply 
 
najiha
najiha
01:05 Jan-05-2006
Re: corrosion rate
----------- Start Original Message -----------
: You seem to be mixing two issues. One is the performance of UT in relation to the resolution of minimum measured thickness. these paramters are a function of the UT technique and the type of corrosion that has occurred.
: Once you have accurate measured data calculating the acceptable minimum wall may depend upon the application and service.
: In Piping you may apply the Barlow Formula or go to API RP 579 and perform Fitness For Service Calculations which will take you beyond the simplistic appraoch in the Barlow Formula.
: Corrosion rate is outlined in documents such as API 570 Inspection of piping and is basically loss Divided by time. The time period you select should be considered relative to the process conditions that have led to the corrosion.
: Understanding the corrosion mechanism will determine how you select your input parameters.
------------ End Original Message ------------

What is the formula for corrosion rates in pipes and pipe fittings?



    
 
 Reply 
 

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