Abstract: While conducting on-site penetration testing of pipeline welding for the nuclear power plant (NPP), in some special cases one has to encounter the situation where the temperature is lower than the standard temperature range and the humidity is higher than the specification. On this higher temperature environment and lower temperature medium, undertaking the test needs not only to consider the procedure, but also to consider the surface of the welds affected by temperature. The paper analyzes the problems and proposes testing procedures and standards to meet the testing requirement by such an environmental situation. Some points needed to be noted are also mentioned.