The Township Clerk shall cause the seal to be affixed to all instruments, documents and writings when required or authorized by law or any ordinance or resolution of the Council. The Clerk shall also cause the seal to be affixed when necessary to exemplify or certify any act or paper which, from the records of his office, shall appear to have been an official act of the Township or a true copy of any official instrument, document or writing of the Township. He shall not affix the seal or cause or permit it to be affixed to any instrument, document or other writing except as herein above provided.