In addition to the correct welding parameters when welding stainless pipelines, it is also essential to ensure adequate welding conditions within the pipeline where the weld root is being welded. The root must meet high quality in mechanical and in chemical properties for dedicated use in nuclear as well as in process technology. Weld root is protected by blowing the shielding gas into the pipeline, whose volume is limited by the use of the barriers. These are divided according to the purpose of use and the material from which they are made. In this thesis, we focused solely on barriers made of water soluble paper which are used in pipelines where after completion of the weld we can no longer interfere. Adverse conditions, such as pressure change, have a strong impact on the conditions for establishing an appropriate atmosphere inside the pipeline. We have concluded that certain chamber atmosphere can only be provided at atmospheric pressure. If this is not the case, the use of water-soluble paper is inappropriate and a different solution needs to be found.