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Results 1 to 21 of 21
  1. #1
    Validation Analyst
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    Panchkula, Haryana
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    Thumbs up Dead Legs in Water System

    Hi all,

    What is the current standard for Dead leg in Purified water / WFI systems.

    As per proposed rule of FDA is 6D. Is there any changes in current regulations?


    Please clarify me.

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  3. #2
    jalal29
    Guest

    Default dead leg

    Hi,

    new regulation are saying 2d rules, and if you can use sanitary valve (zero dead leg), it will be better for you.

  4. #3
    Validation Guru
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    Default

    What regulation is that? I've only heard that 2D or sanitary valves were best practice. It's impossible to meet 2D on all piping. A whole lot of sanitary piping systems would be out of compliance if they had to meet 2D. I believe 6D is industry standard, and that is based on user specifications (and engineering data) not a regulation. Typically a sanitary piping systems are designed to maintain temperature and flow.

  5. #4
    Validation Analyst
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    Default

    USFDA - GUIDE TO INSPECTIONS OF HIGH PURITY WATER SYSTEMS defines Dead-legs in piping section. The statement is

    One common problem with piping is that of "dead-legs". The proposed LVP Regulations defined dead-legs as not having an unused portion greater in length than six diameters of the unused pipe measured from the axis of the pipe in use.
    Thanks & Regards,
    Noor
    www.noormd.com

  6. #5
    Validation Analyst
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    Nov 2007
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    Question

    2d ?
    But in ISPE baseline, it is 3D?

  7. #6
    Validation Analyst
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    Jakarta - Indonesia
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    Default Dead leg Rule

    Inside ISPE C & Q of Pharmaceutical Water and Steam Systems (2007), it mentions " all branch valves, which separate branch piping from the main loop, will be connected to ensure compliance with the 6-D rule". Inin WHO Supplementary Training Modules (January 2006) on Good Manufacturing Practice Water for Pharmaceutical Use Part 2: Water purification and engineering. it describes that there should be no dead legs (though allowable < 1.5 D), more stringent than the same training material issued in 2003 ; allowable , 2 D). Which one should we follow ? It is only one of physical prevention in term of pipe and fittings, as there are other prevention could be implemented.
    As long as we can control and monitor, and keep the quality of purified water within limits, any rules is acceptable.

  8. #7
    Validation Analyst
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    Question re: deaD LEGS

    Hi guys!

    Hope everyone's doing well. I'm totally new here. I was reading the forum re: dead legs in water system and I couldn't resist asking for a consult about my case: We're putting up a pharmaceutical manufacturing plant for non-penicillin products right now and currently we're on the planning and evaluation of the piping system for the distribution of WPU/Deionized water in our production area. The production area consists of 2 zones: 1. the liquid zone 2. dry/solid zone.The original plan was to put tap water and DI water outlets only in the liquid zone. Later on, we suggested to also put provisions for Tap and DI water outlets in all of the production rooms in the solid area (tableting, encapsulating rooms etc.)to maximize the utilization of the pipe that passes thru the solid zone and for future expansion. However, these outlets would have a separate valve to prevent the flow of water into these pipes when not in used. Would the provisions or inactive outlets and the pipes connected to the outlets still be considered dead legs since it would not be used for the meantime and will only be used upon expansion?

    Bottom line: Is it advisable to put tap and DI water outlets in both liquid and solid zones?

    Your suggestions will be highly appreciated. Thanks!

    Ruthy Shelly
    +63916-6031021

  9. #8
    Validation Guru
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    Default

    Quote Originally Posted by ruthy shelly View Post
    Hi guys!

    Hope everyone's doing well. I'm totally new here. I was reading the forum re: dead legs in water system and I couldn't resist asking for a consult about my case: We're putting up a pharmaceutical manufacturing plant for non-penicillin products right now and currently we're on the planning and evaluation of the piping system for the distribution of WPU/Deionized water in our production area. The production area consists of 2 zones: 1. the liquid zone 2. dry/solid zone.The original plan was to put tap water and DI water outlets only in the liquid zone. Later on, we suggested to also put provisions for Tap and DI water outlets in all of the production rooms in the solid area (tableting, encapsulating rooms etc.)to maximize the utilization of the pipe that passes thru the solid zone and for future expansion. However, these outlets would have a separate valve to prevent the flow of water into these pipes when not in used. Would the provisions or inactive outlets and the pipes connected to the outlets still be considered dead legs since it would not be used for the meantime and will only be used upon expansion?

    Bottom line: Is it advisable to put tap and DI water outlets in both liquid and solid zones?

    Your suggestions will be highly appreciated. Thanks!

    Ruthy Shelly
    +63916-6031021
    Dear Ruthy,
    No. it is better that PW loop must be connected to solid zone , it should be the part of distribution system with in the loop, there must not have any valve which segregate the solid zone line with distribution loop.
    Thanks
    Shahnawaz Sajid (Ph.D)

  10. #9
    Validation Analyst
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    Jan 2008
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    Default

    Dear Shahnawaz,

    Thanks for the quick response. I've considered your suggestion and I've discussed it to the engineering department already. But now they came up with a new concept of not putting any DI and tap water outlets in the solids zone (tableting room, encapsulation room, granulation room, perry gun room). Do you think they're concept is right?

    I'll wait for your reply. Thanks a lot.

    Warmest regards,
    Ruthy Shelly

  11. #10
    Validation Analyst
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    Jan 2008
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    4

    Question

    Dear Shahnawaz and anyone who can help,

    Sir/s, I'll make the question more comprehensive. Listed below are the room assignments that we have in our production area. Can you please help me identify which of those require an active outlet for DI and Tap Water and which necessarily do not? Need to justify it since reckless installation of this water distribution might have problems arising in validation in the future.

    Room Assignments:

    Non-Penicillin Bldg.
    Solids Zone
    1. FBD - Fluid Bed Drier Room
    2. V-Blender / Mixing Room
    3. Perry Gun Granulation Room
    4. Tableting Room
    5. Semi-automatic Encapsulation Room
    6. Dry Granulation Room
    7. Wet Granulation Room
    8. Automatic Encapsulation Room

    Liquids Zone
    1. Liquid Compounding Room
    2. Filling and Capping Room.

    Packaging Zone
    1. Stripping Room
    2. Blistering Room

    Sorry for bring such a dummy about these, I'm totally a newbie. Thanks a lot. Have a nice day!

    Sincerely,
    Ruthy Shelly

  12. #11
    Validation Guru
    Join Date
    Aug 2007
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    241

    Default

    Dear Shelly,


    To install water line connections (either PW or tap water), first u need to see the area requirement, then go for equipment need whether CIP or COP. I would be more of help, if I could go through room data sheet along with plant lay out you can contact me via my e mail.
    Thanks and best regards,


    Quote Originally Posted by ruthy shelly View Post
    Dear Shahnawaz and anyone who can help,

    Sir/s, I'll make the question more comprehensive. Listed below are the room assignments that we have in our production area. Can you please help me identify which of those require an active outlet for DI and Tap Water and which necessarily do not? Need to justify it since reckless installation of this water distribution might have problems arising in validation in the future.

    Room Assignments:

    Non-Penicillin Bldg.
    Solids Zone
    1. FBD - Fluid Bed Drier Room
    2. V-Blender / Mixing Room
    3. Perry Gun Granulation Room
    4. Tableting Room
    5. Semi-automatic Encapsulation Room
    6. Dry Granulation Room
    7. Wet Granulation Room
    8. Automatic Encapsulation Room

    Liquids Zone
    1. Liquid Compounding Room
    2. Filling and Capping Room.

    Packaging Zone
    1. Stripping Room
    2. Blistering Room

    Sorry for bring such a dummy about these, I'm totally a newbie. Thanks a lot. Have a nice day!

    Sincerely,
    Ruthy Shelly
    Last edited by Shahnawaz; 01-25-2008 at 06:23 PM.
    Shahnawaz Sajid (Ph.D)

  13. #12
    Validation Guru
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    Dec 2006
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    Default

    I will say that if you do as you described and close a valve between the main and branch and it is 6d then you probably don't have a "dead leg". A dead leg affects quality of the entire water system by providing a non-circulating water zone. What you have described is much worse in my opinion and would likely affect both the drop and system. The second you open the branch and have the use point closed, you have a dead leg. What is worse, if you didn't flush the branch line properly, you could introduce bio-burden to your whole system

    I won't comment on where drops belong...it is my opinion that validation is not responsible to dictate where water drops go? You are supposed to validate that they are installed, operate and perform according to the specifications.

  14. #13
    Validation Analyst
    Join Date
    Feb 2008
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    2

    Default dead leg



    colleagues new joinee here to boost some what extent.

    dead leg our colleagues described 6D but how much length we can aceept.

  15. #14
    Validation Analyst
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    Panchkula, Haryana
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    Default Regarding Dead legs in water system

    Tnx to paulux

    In WHO, it was mentioned a limit for dead legs is NMT 1.5 D
    But in USFDA, LVP regulations the same was NMT 6D (in consideration of WFI)

    As on today most pharmaceutical firms are designing their water systems with 0 dead legs. But it is not possible for each point. some where there may extend to 0 dead legs.

    We may follow which ever is less (NMT 1.5 D) in a worst case scenario.
    vamse krishna ratnakaram
    vamsemicro@gmail.com

  16. #15
    Validation Expert
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    Feb 2010
    Location
    Sidoarjo
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    125

    Default

    is the deadleg's limit for PW same with WFI or other types of USP water?
    please give me the link for any reference... thanks in advance.

  17. #16
    Validation Expert
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    Feb 2010
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    Sidoarjo
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    Default

    I have got TRS 929 document. in page 63, it mentions: Deadlegs in the pipework installation greater than 1.5 times the branch diameter should be avoided.

  18. #17
    Validation Analyst
    Join Date
    Mar 2010
    Posts
    34

    Default Dead legs in water system

    Dear All
    I agree with Mr. vamsemicro to follow dead leg NMT 1.5 D (Ref WHO) in pharmaceutical water system as it is generally accepted as current industry standard. Secondly I don’t find any problem in achieving dead leg less than 1.5 D because of availability ultra modern orbital weld machines which requires only 12 mm clearance on both side of weld. Practically Zero dead valves (i.e. block valve like GEMU) are available in market that too with inbuilt sampling port. Now a day many fields instrumentation like pH/cond meter/pressure sensors are also available in a manner to minimize the formation of dead leg.
    As mentioned in many post of this thread it is true that there are guidelines expecting <6D, <3D & <1.5D too. The expectation of regulatory agencies is becoming more stringent day by day because of technological advancement.
    Secondly it’s my opinion that it is always better to built quality by design itself rather than relaying on its control & monitoring because the risk of failure & their consequences are too bad in later case.
    Dead leg NMT 1.5 D can equally be made applicable for purified water system too based on criticality of application.

    However following abstract from SD-3.11 system design (ASME BPE-2007) Hope you will find this useful while constructing the system.
    Dead leg is measured by term L/D, Where L –Leg extension, D-Id of pipe,
    For high purity water & clean steam systems, L/D of 2:1 is attainable. However if dead leg 2:1 is not achievable with certain bio-processing equipments L/D of 2:1 or less shall be considered a target ratio & shall not be construed to be an absolute requirement. This guideline has also given tabular information on L/D for flow through Tee of various sizes with blind cap.

    Regards
    Ravi Dhanbhar

  19. #18
    Validation Analyst
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    Default

    Dead leg, is a region, pipeline, where water can be stopped and if the water was not changed during washing. Bacteria tube lengths stalemate and cracks is being protected from exhaust and sanitation practices and can recontaminate pipes.

  20. #19
    Validation Guru
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    Default

    A dead leg is any area in a piping system where water can become stagnant and where water is not exchanged during flushing. Bacteria in dead-end pipe lengths and crevices are protected from flushing and sanitization procedures and can recontaminate the piping system. Modern piping design limits the length of any dead-end pipe to 6 times the pipe’s diameter (even shorter dead legs are preferred). This is the six diameter rule.


    GUIDE TO INSPECTIONS OF HIGH PURITY WATER SYSTEMS http://www.fda.gov/ora/inspect_ref/igs/high.html says

    The proposed LVP Regulations defined dead-legs as not having an unused portion greater in length than six diameters of the unused pipe measured from the axis of the pipe in use. It should be pointed out that this was developed for hot 75 - 80oC circulating systems. With colder systems (65 - 75oC), any drops or unused portion of any length of piping has the potential for the formation of a biofilm and should be eliminated if possible or have special sanitizing procedures."

    As per ASME BPE 1997 : " For Bioprocessing systems, L/D of 2:1 is achievable with today's design technology for most valving and piping applications"
    Durga Prasad

  21. #20
    Validation Guru
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    Default Astm- asme & bpe standards

    ASTM- ASME & BPE Standards and their application in Pharmaceutical industry.
    By William M. Hut
    Published in PDA Journal of Pharmaceutical science and technology.2011
    Durga Prasad

  22. #21
    Banned
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    Apr 2011
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    Indore
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    10

    Default

    Hi all,
    my one quation to the discussion about deadlegs, is there in failure event observed in any pharma compny because of <6D deadleg? what is is resion that we want to reduce this to <1.5D?
    Pls. share any incident known to the group
    Last edited by sweet.sandeep; 04-28-2011 at 07:59 AM.

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