Re: CHEMICAL CLEANING FOR NEW PIPLEINES

From: <Gang>
Date: Sat Aug 02 2003 - 01:26:00 EDT

Dear colleague,
The query does not specify the job conditions, like, the material of construction, service, operating pressure, operating temperature, etc.
One probable reason could be the flexibility analysis. The pipeline may appear to be perfectly OK after undergoing all the prerequisites as the welding procedure, physical examination and NDT checks, stress relieving, cleaning and all that. The pipe supports are to be executed as per the recommendations of the stress engineer, and if possible, endorsed by him/her, of course, if the line is to operate at a high temperature. The slightest negligence in this matter, as to provide the required gaps at guides, providing the correct directional stops, proper fixation at the anchors, the right placement of the spring hanger, locking / unlocking of the spring, etc. can result in unimaginable values of stress concentrations at certain locations which ultimately can lead to failure, when the hot process fluid is admitted into it.
Well, you may check up this aspect of the line. The other could be the MOC itself. The compatibility of the material with respect to the service fluid may once again be checked. It could be traced to corrosion as well.
Please present the complete case study so that someone could analyze it properly.

• e-Director <segip@tm.net.my> wrote:
  > Dear friends,
  >
  >
  > Recently, during our plant start-up, some of our
  > newly welded joints burst
  > and break-off. To date, there had been no finding
  > to the cause of these
  > problems..
  > Some of the guys suggested that maybe the welded
  > joint needs to undergo
  > chemical cleaning to remove any unwanted
  > contaminants that may cause
  > flammabality such as oil and grease and other debris
  > inside the
  > pipelines.... The HAZ area inside the welding joint
  > may also cause the
  > welding joint to be weak and also stresses the need
  > for chemical cleaning...
  >
  > 1. Does anyone knows why we need to do chemical
  > cleaning for a new
  > pipelines?
  > 2. Does this chemical cleaning process also need to
  > be done if we do some
  > modification in the lines which involves a lot of
  > welding procedure?
  > 3. Is it possible that without chemical cleaning,
  > there is a danger of
  > explosions?
  >
  > Thanks
  >
  >
  >
  >
  >
  >
  >
  

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