Amazon.com: Structural Pipe Fitting, DIY Outdoor, Use Imagination -1-1/2"Tee-E Short, 3T-8, Aluminum Magnesium, Note: ID of fitting is 1.925, to take nominal 1-1/2" steel pipe which all have an OD of 1.9". :
Threaded Connector | Buy Aluminum Threaded Fittings & Connectors for Air Pipe Systems - Aluminum Air Pipe
Amazon.com: Structural Pipe Fitting, 1-1/4" Cross - E Short, 21X-7, Aluminum Magnesium, Please note. ID of fitting is 1.68, to take nominal 1-1/4" steel pipe which all have an OD of 1.66". :
Pipe Fittings for 1-1/4" and 1-1/2" Schedule 40 Pipe