This paper investigates the influence of primer on mechanical properties and fracture behavior for ring specimens, prepared from the commercial chlorinated polyvinyl chloride (CPVC) pipe. After immersing the specimens in primer for 30 min, the specimens were dried for eight different periods, ranging from half day to 113 days, and then fractured in tension along the hoop direction. The results suggest that the longer the drying time, the higher the recovered strength. After the longest drying time of 113 days, the primer-affected-zone showed strength recovery up to 63% of the strength for the virgin pipe. However, such a level of recovery cannot be achieved for ductility. The examination of specimens indicated that the exposure to primer created a core–shell structure on the cross section, of which the area ratio was independent of the drying time. It is believed that exposure to primer caused swelling and formed the shell region. The presence of the shell region has two roles in the ductility reduction. One is to provide multiple sites along the border between the shell and the core regions for crack initiation and the other to enhance stress concentration at the crack tip. This paper concludes that exposure to primer in the solvent welding process may reduce ductility of the CPVC pipe, thus affecting its resistance to slow crack growth in long-term applications.

A refined one‐slit‐ring method is presented to characterize residual hoop stress distribution in pipe ring specimens of inhomogeneous cross section. Although the original one‐slit‐ring method enables determination of residual hoop stress distribution through slitting single ring specimen in the axial direction, its use is limited to specimens of uniform material properties. This work is to extend applicability of the method to ring specimens with a cross section of core–shell structure. Chlorinated polyvinyl chloride (CPVC) pipe is used in the study, and core–shell structure in its ring specimens is introduced through immersion in primer for 30 min. Analytical expression for the residual hoop stress distribution in these specimens is derived, and verified using finite element (FE) simulation which uses a temperature gradient field to generate stress so that diametrical change by the slitting is same as that measured experimentally. Results from the analytical expression agree well with those from the FE simulation, showing decrease of the residual hoop stress by the exposure to primer, and the extent of decrease depends on the drying time after the immersion in primer, to about half of its original value after 30 days of drying, and then remains relatively constant afterwards. POLYM. ENG. SCI., 59:E296–E309, 2019. © 2019 Society of Plastics Engineers

Hydronic systems installed in buildings utilize water to transport thermal energy within the building for heating and cooling purposes. These systems can be closed loop, where the water is chemically treated and circulated indefinitely, or they can be open loop, where the water is not treated and is effluxed as a result of occupant activities, such as bathing or cooking. Water in an open loop system may circulate within the system for a limited time before it is extracted from the system by occupant activities and replaced with new water from the local water supply. The implementation of open loop hydronic systems is becoming more common in multi-unit residential buildings, even though a number of questions regarding the use of such systems remain unanswered. One concern regarding the use of circulated potable water for heating purposes is the potential effects on the occupant perceptions of the palatability of the service water being delivered to their suites. In an open-loop HVAC system (Heating Ventilating, Air Conditioning System), heating water is subject to repeated thermal cycles and continuous recirculation, which creates the potential for chemical alterations of the materials present in the water or leaching of materials from the equipment and piping. Through the use of Flavor Profile Analysis (FPA) established by the American Water Works Association, and a multi-unit HVAC system constructed in a controlled environment, the palatability effects of the operational system were evaluated for a number of scenarios. The collected feedback from the study participants was then tabulated to quantify the impacts of using potable water as a recirculating heating medium on the perceptions of the occupants. The resulting observations led us to conclude that utilizing potable water as a heating medium has a negligible effect on the palatability of water in the system for average retention times under one day, and a non-objectionable, but noticeable, effect for higher average retention times.

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