Tees and stub-ins are a joint of two cylindrical shells and can be of the following types:

Features of ASME code:

Modeling T-shaped Joints

If tee element is not added to a node, the joint is modeled as 3 pipe connection, without rigid element, without flexible hinge and tee stress is not calculated.

Fig. 1. Modeling a intersection of two pipes without a tee

If any type of tee is added into the intersection node, then you can specify tee length (L), tee height (H), header wall thickness, and branch wall thickness.

If you don't specify tee length (L) and tee height (H) then only rigid element 10-20 (H=Dh/2, Dh – header outer diameter) inserted. Weight of rigid element, fluid and insulation is zero

When you run analysis simple tee model is automatically replaced by complex model. Added 6 additional nodes (21, 2, 3, 4, 5, 20). Nodes are hidden for user. It is visible only in developer mode.

This is the tee object model that you see in START-PROF:

And this is the real tee model, that is used inside the software. The header and branch pipes have a different wall thickness than the connected pipes. The special flexible springs are added to model the header (2) or branch (1) flexibility if ASME B31J is used. The rigid element always used to remove the "dummy" flexibility of the branch element (3)

For “Custom Tee” and for any standard tee if ASME B31J code selected, additional run flexibilities added into nodes 4 & 5, and branch flexibilities added into node 20. Flexibilities calculated according to ASME B31J

If “Consider Tee Branch Flexibility” option selected, then 4 & 5 nodes are not created for standard tees. The flexibilities in node 20 calculated according to the standard selected in Project Settings. For ASME and DL/T 5366-2014 the standard is ASME BPV SIII div 1 class 1 NB 3686, flexibility is considered for reducing tees with Db/Dh<0.5. For Russian codes flexibility is considered for reducing tees with Db/Dh<0.8.

Tee weight Q is distributed along the header pipe L, q=(Q-qp*L1)/L, qp - pipe connected to branch weight, L1=H-D/2 - branch length. The rigid element length is zero. The weight of pipes covered by tee is removed. The insulation and product weight is the same as on connected pipes. Snow, ice, wind, and user defined uniform loads are got from connected pipes.

Calculating Tee Stress

Stress in tees is calculating taking into account concentration (intensification) factors, which indicate to what degree these stresses exceed bending stress in branch or header cross-sections without weakness caused by the stub-in. Formulas for calculating the intensification factor are given in  standards. Equivalent stress is calculated for three tee cross-sections 1, 2, 3 (fig. 3). The greater value is used in analysis.

1 - hidden, automatically added node

Fig. 3. Tee cross-sections (1,2,3) for stress analysis

Menu and Toolbar Access

To insert an element, select the desired node and use: Insert > Insert Tee

To view properties of an existing element: