There is no place to download a NCCER Pipe Fitter practice test online because there is no official practice test available. According to the official NCCER website, the organization does not produce any study guides or practice tests.
Although there are no practice tests available for download, the necessary requirements for certification are available on the NCCER website for download on their "Assessment and Performance Verifications" pages. Visitors can download information on all the areas covered by this assessment and others at this site. These documents serve as a guide for test evaluators and thus are a reasonable source of information on the type of questions that appear on the exam.
In addition to assessment overview documents, NCCER offers e-books through Pearson Custom Library. Users can create custom e-books on a chapter-by-chapter basis. For pipe fitting, there are four trainee guides available, each corresponding to the four levels of pipe fitting. These guides cover topics such as tools, trade math, pipe fabrication, pipe installation, rigging, motorized equipment, underground excavation, pipe testing, blueprint reading, special piping, valves and supervision. These books are useful for self-study and to help test-takers pass exams. Print versions of these exams are also available through online book retailers such as Amazon.